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The paper provides an overview of the significance of nanomaterials as additives, in the tribological performance of lubricants. This review describes the ascendancy of different nanoparticles such as carbon-based nanoparticles, metallic nanoparticles, oxide nanoparticles, sulphide nanoparticles, nanocomposites, hybrid and bimetallic nanoparticles in lubricants. The study also evaluates the underlying principles of lubricant-nanoparticle interactions and their effects on wear prevention and friction reduction. The key parameters including particle morphology, particle size, weight concentration, and functionalization of the particle surface, that determine the friction and wear characteristics are discussed. Also, the science behind surface interaction and various mechanisms involved in friction and wear modification is described. The review highlights the prospect of various nanomaterials in the field of lubrication and facilitates development of advanced nanolubricants with superior tribological properties, that attributes to the reduction in energy consumption and improved performance.

Reverse micelles as nanosized aqueous droplets existing at certain compositions of water-in-oil microemulsions are widely used today in the synthesis of many types of nanoparticles. However, without a rich conceptual network that would correlate the properties and compositions of reverse micellar microemulsions to the properties of to-be-obtained particles, the design procedures in these cases usually rely on a trial-and-error approach. As like every other science, what is presently known is merely the tip of the iceberg compared to the uninvestigated vastness still lying below. The aim of this article is to present readers with most of the major achievements from the field of materials synthesis within reverse micelles since the first such synthesis was performed in 1982 until today, to possibly open up new perspectives of viewing the typical problems that nowadays dominate the field, and to hopefully initiate the observation and generation of their actual solutions. We intend to show that by refining the oversimplified representations of the roles that reverse micelles play in the processes of nanoparticles synthesis, steps toward a more complex and realistic view of the concerned relationships can be made.

The first two sections of the review are of introductory character, presenting the reader with the basic concepts and ideas that serve as the foundations of the field of reverse micellar synthesis of materials. Applications of reverse micelles, other than as media for materials synthesis, as well as their basic structures and origins, together with experimental methods for evaluating their structural and dynamic properties, basic chemicals used for their preparation and simplified explanations of the preparation of materials within, will be reviewed in these two introductory sections. In Secs. 3 and 4, we shall proceed with reviewing the structural and dynamic properties of reverse micelles, respectively, assuming that knowledge of both static and dynamic parameters of microemulsions and changes induced thereof, are a necessary step prior to putting forth any correlations between the parameters that define the properties of microemulsions and the parameters that define the properties of materials synthesized within. Typical pathways of synthesis will be presented in Sec. 5, whereas basic parameters used to describe correlations between the properties of microemulsion reaction media and materials prepared within, including reagent concentrations, ionic strength, temperature, aging time and some of the normally overlooked influences, will be mentioned in Sec. 6. The whole of Sec. 7 is devoted to reviewing water-to-surfactant molar ratio as the most often used parameter in materials design by performing reverse micellar synthesis routes. The mechanisms of particle formation within precipitation synthesis in reverse micelles is discussed in Sec. 8. Synthesis of composites, with special emphasis on silica composites, is described in Sec. 9. All types of materials, classified according to their chemical compositions, that were, to our knowledge, synthesized by using reverse micelles up-to-date, will be briefly mentioned and pointed to the corresponding references in Sec. 10. In Sec. 11, some of the possible future directions for the synthesis of nanostructured materials within reverse micelles, found in combining reverse micellar syntheses and various other synthesis procedures with the aim of reaching self-organizing nanoparticle systems, will be outlined.

The hydrogenation activity and sulfur-tolerant ability of nano-NiMo catalysts prepared by sol–gel method were investigated by hydrogenation of ethylbenzene containing thiophene. The results show that the adding of molybdenum has a profound effect on the structure and the sulfur-tolerant ability of nickel-based catalyst. The catalyst with MoNi ratio of 0.16 showed maximum hydrogenation activity and good sulfur resistance when compared to other catalysts. It seems that new hydrogen-adsorbed phase is formed at high temperature and the quantity of hydrogen adsorbed increases greatly when Mo is added to the nickel-based catalysts.

The amorphous phase (AP) and nanocrystalline particle (NP)-reinforced composite coating was fabricated by laser cladding (LC) of the Ni45-WC mixed powders on the 304 stainless steel. An LC technique favored APs as well as NPs to be formed due to their rapid cooling and solidification characteristics, so the wear resistance of the Ni-base coating was improved. Microstructures and wear resistance of the fabricated composite coating were studied extensively. The test results showed that the microhardness and wear resistance of this LC coating were enhanced under the actions of NPs, APs and the ceramics. The study of the laser synthesis of NPs provided a theoretical basis for improving the LC technique.

As research on new technologies for the creation of flexible electrochemical energy storage systems continues, they are widely used in industries such as public portable devices, mobile electronics, and electronic products worldwide. Flexible supercapacitors (FSCs) are widely used in wearable electronics and medical fields, with high power density, excellent mechanical integrity and cycle stability. Researchers devoted a lot of time in recent years promoting several kinds of transition metal oxides (TMOs) for SCs. Organometallic frameworks (MOFs) are commonly utilized for the production of metal oxide-based electrodes for high-performance SCs as precursors or templates. These MOF-based metal oxides have a porous and adjustable structure, a large specific surface area, strong electrical conductivity, and good electrochemical stability, and they fulfil the specific capacitance and long-cycle power requirements of electrochemical double-layer capacitors. The latest developments in the production and application of MOF-derived metallic oxide compounds in FSCs are summarized in this study.

Explosives can be divided into low and high, the efficient detection of which is of utmost importance for security reasons. A major component of high explosives is the nitroaromatic compounds. These explosives, when sealed, have difficulty detecting. In this review work, the major techniques for explosive detection i.e. animal olfaction, calorimetric sensors, immunosensors, ion mobility spectrometry, and Raman spectroscopy are discussed. The materials or compounds comprising nitroaromatic sensors have been a topic of major research for the last three decades. Nanomaterials do provide an acceptable solution for portable, affordable, and efficient detection of analytes of explosive nature due to their redox properties. 3D nanomaterials like TiO₂, Au, SiO₂, Ag and CdSe-ZnS, 0D materials like CdSe, CdTe, ZnS and MoS₂ can detect nitroaromatic compounds efficiently. In the upcoming technology, the incorporation of quantum dots is also considered for explosive detection. As an option for prospective research in the field, development in the use of boron nitride for detecting explosives is also a good option. A comprehensive review of such materials is discussed in this review paper.

The effect of iron content on the structure, morphology and magnetic properties of (Ni${}_{60}$Co${}_{40}$)${}_{100-}$${}_x$Fe${}_x$ powders synthesized by hydrothermal method has been studied. Several samples have been elaborated for different Fe content ($x$= 0, 3, 5, 7, 10 and 13.5). The as- prepared samples have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometry (VSM). From XRD spectra and for all Fe content, we have shown the presence of both face centered cubic (FCC) and Hexagonal (HCP) nanosized phases. The lattice parameter increases with increasing Fe content and the grains size varies with Fe content to reach a minimum value of 32 nm for (Co${}_{40}$Ni${}_{60}$)${}_{90}$Fe${}_{10}$. From hysteresis curves, we have extracted the saturation magnetization, Ms, and the coercivity, Hc. We noticed that Ms increases and then decreases as a function of Fe content. The values of Hc vary from 156 Oe to 186 Oe depending on the particles shape.