Adsorption of Oligomeric Peroxides on Aerosil and Magnesium Oxide and Their Behavior on the Water-Air Phases Interface

Oligomeric peroxide adsorption of sebacic acid on aerosil and magnesium oxide was studied. Adsorption process parameters were found. It is shown that the adsorption takes place through the hydrogen bonds formation between OH– groups of adsorbents surface and peroxide groups. The adsorption process suggests the behavior of peroxide compounds on the water-air phase’s interface. Monomolecular film formations on water surface for oligomeric peroxides were studied. It was found that calculated values of the area extrapolated to zero pressure (S0) depend on the solvent which was used to apply the peroxide in the phases interface. Oligomeric peroxide monolayers considered as condensation-type monolayers. Thermal decomposition of oligomeric peroxide and its di- and monoperoxide analogues was studied. It was shown that total constants of thermal degradation rate k for oligomeric peroxide are higher than those for di- and monoperoxide analogues. There is a correlation between S0 calculated values and the constants of thermal degradation rate for oligoperoxide. The less is S0 value the higher is k value. The conformational state of the macromolecule was preserved during transferring the oligomeric peroxide solution in an organic solvent to the phases interface that affects k values.

Comparison of the temporal efficacy of Aquatain surface films for the control of Anopheles arabiensis and Ochlerotatus caspius larvae from Sudan

Aquatain mosquito formulation (AMF) is a surfactant that spreads across the surface of water bodies to produce a monomolecular film. This study experimentally evaluates the temporal efficacy of AMF against aquatic stages of Anopheles arabiensis and Ochlerotatus caspius under laboratory conditions. Using the recommended application dose of 1 ml m −2 , a large species-specific difference in the median lethal time for L3–L4 larvae was observed. The median lethal time to 50% mortality (LT50) and 90% mortality (LT90) was 1.3 h, 95% CI [1.2, 1.4] and 3.8 h, 95% CI [3.6, 4.0], respectively, for Oc. caspius . The corresponding values for An. arabiensis were 8.1 h, 95% CI [7.3, 9.0] and 59.6 h, 95% CI [48.5, 76.2]. Based on data from published laboratory studies for a total of seven mosquito species, drawn from four genera, results in the following three groups, [LT50 = 1–2 h, Culex quinquefasciatus , Ochlerotatus caspius ] [LT50 = 8–24, hours, Anopheles minimus , Anopheles arabiensis, Anopheles gambiae s.s.] and [LT50 = 72–143 h, Anopheles stephensi , Aedes aegypti ]. In all experiments, 100% mortality was achieved given sufficient time. The potential relevance of mortality rate estimates, in the context of other studies, on the use of monomolecular films for the control of malaria and arbovirus diseases is discussed.

Preparation of nano-raspberry particles using chemically adsorbed monolayers

ABSTRACTNanoparticles are often used for both metals and non-metals, in cosmetics, home appliances, electrical products, as well as paints and inks. Nanoparticles are commonly produced by the vapor phase method or the liquid phase method. However, it is still difficult to produce nanoparticles with complicated shapes, such as raspberry-shaped particles. In this study, we demonstrated that nano-raspberry particles can be made by coating the surface of the small- and the large-sized silica nanoparticle with a reactive, chemically adsorbed, monomolecular film and then by bonding the smaller nanoparticles to the surface of the larger nanoparticle. Furthermore, by preparing a fractal surface structure on a flat substrate surface, a super-water and oil repellent surface, which can potentially improve the application performance, was successfully produced.

Nonlinear chiral rheology of phospholipid monolayers

The macroscopic, mechanical response property of a monomolecular film of the phospholipid DPPC is chiral: values of nonlinear elastic moduli and yield stresses are quite different, depending on the direction of the applied torque; even healing processes after removing a large torque also exhibit completely different behaviors.

Self-Protecting Disk Lubricant: D-MH2

In disk drives of current generation, the thickness of the disk lubricant has been reduced to the level of a sub-monomolecular film. For a mono- or a sub-monomolecular film of a perfluoropolyether terminated with a primary hydroxyl unit at both ends, each lubricant molecular chain is chemically bound to the carbon substrate at both termini, and if it has a hydrocarbon sector inserted at its center, the hydrocarbon sectors would assemble at the top of the film. They are thus poised most aptly to react as a Lewis base (an electron donor) to the Lewis acid centers on the slider thus abating the Lewis acid-catalyzed lubricant degradation. A TOF-SIMS study of lubricant films of various thicknesses was performed. The study substantiated the envisaged lubricant posture.

Disk Lubricants of Ultimate Design

In disk drives of current generation, the thickness of the disk lubricant has been reduced to the level of a sub-monomolecular film. For a mono- or a sub-monomolecular film of a perfluoropolyether terminated with a primary hydroxyl unit at both ends, each lubricant molecular chain is chemically bound to the carbon substrate at both termini, and if it has a hydrocarbon sector inserted at its center, the hydrocarbon sectors would assemble at the top of the film. They are thus poised most aptly to react as a Lewis base (an electron donor) to the Lewis acid centers on the slider thus abating the Lewis acid-catalyzed lubricant degradation.

Bulk flow driven by a viscous monolayer

The flow in the bulk driven by a viscous interfacial film set in motion by a rotating sharp circular knife edge has been examined through experiments and computations. In the experiments, the water surface is covered by an insoluble monomolecular film of dipalmitoylphosphatidylcholine (DPPC), a molecule of wide interest in biology and medicine. It is shown that the viscous coupling between the interfacial film and the bulk liquid leads to a strong bulk flow. Depending on the surface packing and corresponding surface tension, DPPC monolayers exhibit a wide range of phase morphologies. Upon shearing the monolayer, its viscous response varies from that of an essentially inviscid film at low surface packing, to that of a highly viscous non-Newtonian (shear thinning) film when the packing is dense. The more viscous the film, the stronger the driven bulk flow. We have examined this behaviour for hydrodynamic regimes straddling the Stokes flow regime and where flow inertia is important.