Formation of a surfactant adsorption layer on microroughnesses of friction surfaces

Formation of an adsorption surface layer on microneralities of friction surfaces. The model of interaction of the molecule of surface-active substance with the microasperity of friction surface has been given. It has been found that the distance of interaction and the thickness of an adsorbed layer of surface-active substances depend on value of a field of an adsorbing surface and energy of thermal oscillations of molecules of surface-active. It has been shown that the distance of interaction and the thickness of an adsorbed layer of surface-active substances decrease at magnification of temperature of working liquid.

Protein Adsorbate Biohybrids and Sequential Hystallosteric Protein Adsorption

Protein adsorption on solid surfaces is characterized by multivalence, binding-unit overlap, sequential adsorption, surface allosterics, lateral interactions and pronounced adsorption-desorption hysteresis, giving rise to the sequential, hystallosteric, adsorption model ("SHA model"). Adsorption isotherms of fibrinogen on a titanium miniplates and of the growth factors rhBMP-2 and rhVEGF165 on PDLLA nanofiber fleeces are presented. Controversial Langmuir type isotherms of fibrinogen and rhVEGF165 can be understood on the basis of singular long-lived metastable states central to the SHA-model.

Manipulation of the Magnetic Properties of Janus WSSe Monolayer by the Adsorption of Transition Metal Atoms

Two-dimensional Janus materials have great potential for the applications in spintronic devices due to their particular structures and novel characteristics. However, they are usually non-magnetic in nature. Here, different transition metals (TMs: Co, Fe, Mn, Cr, and V) adsorbed WSSe frameworks are constructed, and their structures and magnetic properties are comprehensively investigated by first-principles calculations. The results show that the top of W atom is the most stable absorption site for all the TM atoms, and all the systems exhibit magnetism. Moreover, their magnetic properties significantly depend on the adsorbed elements and the adsorbent chalcogens. A maximal total magnetic moment of 6 μB is obtained in the Cr-adsorbed system. The induced magnetism from S-surface-adsorption is always stronger than that for the Se-surface-adsorption due to its larger electrostatic potential. Interestingly, the easy magnetization axis in the Fe-adsorbed system switches from the in-plane to the out-of-plane when the adsorption surface changes from Se to S surface. The mechanism is analyzed in detail by Fe-3d orbital-decomposed density of states. This work provides a guidance for the modification of magnetism in low-dimensional systems.

Friction mechanism and characteristics of reticle based on contact theory

With the development of integrated circuits, the structure of chips becomes more and more complex, and the processing cost increases accordingly. In order to improve the productivity of lithography, the acceleration of reticle stage should be increased to reduce the positioning time. However, the increase of acceleration will cause the relative slip between reticle and vacuum chuck, which seriously affects the accuracy and product yield of lithography. In order to suppress the slippage, the friction mechanism and characteristics between reticle and chuck are studied in this paper. Firstly, based on KE contact model and MB fractal contact model, the maximum static friction coefficient model between nano-scale surfaces was established. Then, the surface morphology parameters of reticle and chuck adsorption surface was obtained by atomic force microscopy (AFM) scanning. Finally, the maximum static friction force experiments show that the MB model is more suitable for the study of friction mechanism between reticle and vacuum chuck, and the model is more instructive for the suppression of reticle slip.

Manipulation of The Magnetic Properties of Janus WSSe Monolayer By The Adsorption of Transition Metal Atoms

Two-dimensional Janus materials have great potential for the applications in spintronic devices due to their particular structures and novel characteristics. However, they are usually non-magnetic in nature. Here, different transition metals (TMs: Co, Fe, Mn, Cr, and V) adsorbed WSSe frameworks are constructed, and their structures and magnetic properties are comprehensively investigated by first-principles calculations. The results show that the top of W atom is the most stable absorption site for all the TM atoms, and all the systems exhibit magnetism. Moreover, their magnetic properties significantly depend on the adsorbed elements and the adsorbent chalcogens. A maximal total magnetic moment of 6 μB is obtained in the Cr-adsorbed system. The induced magnetism from S-surface-adsorption is always stronger than that for the Se-surface-adsorption due to its larger electrostatic potential. Interestingly, the easy magnetization axis in the Fe-adsorbed system switches from the in-plane to the out-of-plane when the adsorption surface changes from Se to S surface. The mechanism is analyzed in detail by Fe-3d orbital-decomposed density of states. This work provides a guidance for the modification of magnetism in low-dimensional systems.

METHYLENE BLUE REMOVAL FROM RESIDUAL WATER USING FIR WOOD SAWDUST AS ADSORBENT

Methylene blue is generally used as dyeing agent in textile, printing and pharmaceutical industries, which leads to the obtaining of large amounts of wastewater. The purpose of this study is to remove methylene blue dye from aqueous solutions using fir wood sawdust waste as low cost biosorbent material. In order to evaluate the adsorption process, analyses for determination of micrometric properties, infrared spectroscopy, optical microscopy and colorimetry were performed. To increase the efficiency of the process and the adsorption surface, the fir wood sawdust was grinded and sieved. Some specific parameters were varied in the experimental part in order to study the influence of the adsorbent support dose, concentration, temperature, contact time, volume and stirring rate. The removal efficiency of methylene blue dye was further studied for evaluating the adsorption capacity of the fir wood sawdust.

Detection of Impurities in Water Using Nanostructures

Saltpeter negatively affects the human body, it contributes to the formation of a dangerous substance in the blood – methemoglobin, which leads to oxygen starvation. An increase in methemoglobin up to 60% leads to a fatal outcome. Also, the excess of saltpeter in water causes poisoning, disorders of the gastrointestinal tract, excretory and endocrine systems, the destruction of tooth enamel and the appearance of caries. Saltpeter can be determined in water by chemical analysis of the liquid, as well as using nanomaterials. These structures have a sufficiently highly developed adsorption surface, this property helps to detect the presence of saltpeter in water, and at the same time to clean it. The results of the studies made it possible to establish that after passing water with an admixture of saltpeter, the concentration of the latter decreased. Thus, the theoretical calculations showing the possibility of saltpeter adsorption by carbon nanotubes were confirmed. The obtained results and the applied methods can be used in conducting complex high-performance water examinations.

Sorption Mechanisms of Chemicals in Soils

Sorption of chemicals onto soil particle surfaces is an important process controlling their availability for uptake by organisms and loss from soils to ground and surface waters. The mechanisms of chemical sorption are inner- and outer-sphere adsorption and precipitation onto mineral surfaces. Factors that determine the sorption behavior are properties of soil mineral and organic matter surfaces and properties of the sorbing chemicals (including valence, electron configuration, and hydrophobicity). Because soils are complex heterogeneous mixtures, measuring sorption mechanisms is challenging; however, advancements analytical methods have made direct determination of sorption mechanisms possible. In this review, historical and modern research that supports the mechanistic understanding of sorption mechanisms in soils is discussed. Sorption mechanisms covered include cation exchange, outer-sphere adsorption, inner-sphere adsorption, surface precipitation, and ternary adsorption complexes.

Magnetic Fe3O4@Mg/Al-layered double hydroxide adsorbent for preconcentration of trace metals in water matrices

A magnetic Fe3O4@MgAl-layered double hydroxide (MLDH) nanocomposite was successfully synthesized and applied as an effective adsorbent for preconcentration of trace As(III), Cd(II), Cr(III), Co(II), Ni(II), and Pb(II) ions from complex matrices. The quantification of the analytes was achieved using the inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The nanocomposite was then characterized using BET, FTIR, SEM, and EDS. Due to its high adsorption surface area, compared to traditional metal oxide-based adsorbents, MLDH nanocomposite exhibited high extraction efficiency. Several experimental parameters controlling the preconcentration of the trace metals were optimized using response surface methodology based on central composite design. Under optimum conditions, the linearity ranged from 0.1 to 500 µg L−1 and the correlation of coefficients (R2) were higher than 0.999. The limits of detection (LODs) and quantification (LOQs) were 0.11–0.22 µg L−1 and 0.35–0.73 µg L−1, respectively. The intra-day (n = 10) and inter-day precisions (n = 5 working days) expressed in the form of percent relative standard deviations (%RSDs) were below 5%. The proposed method was successfully applied for the analysis of the As(III), Cd(II), Cr(III), Co(II), Ni(II), and Pb(II) ions in different environmental water samples.