Search results

The purpose of this paper is to develop a potential nanoparticles lubricant additive for solving the problem of the insolubility and stable dispersity; the complex nanoparticles with core-shell structures are less studied in the field. Therefore, this paper determines novel complex nanoparticles and their tribological properties.

According to the conventional preparation method, the complex nanoparticle styrene/calcium borate (PS/O-CaB) was synthesized. The microstructures of the as-obtained samples were characterized by X-ray diffraction infrared spectroscopy and thermogravimetric analysis. Tribological properties of PS/O-CaB used as lubricating oil additive were evaluated on four-ball tribometer. The worn surface of the steel ball was investigated by a three-dimensional non-contact surface profilometer and X-ray photoelectron spectroscopy (XPS).

The results of the structure characteristic indicate two different crystalline forms, namely, Ca₂B₆O₁₁ and Ca₂B₂O₅, and the average size of calcium borate nanoparticles in PS/O-CaB is about 20-40 nm. Moreover, the good tribological properties are due to a wear resistance film containing both depositions and the tribochemical reaction products which comprise B2O3, FeB and Fe2O3.

Novel complex nanoparticles with core-shell structure (PS/O-CaB) were successfully prepared. Moreover, the PS/O-CaB shows excellent tribological capacity such as load-carrying, friction-reducing and antiwear property.

Enzymatic desizing using α-amylase is the conventional and eco-friendly method of removing starch based size. Conventionally, enzymes are drained after completion of process; being catalysts, they retain their activity after reaction and need to be reused. Immobilization allows the recovery of enzymes to use them as realistic biocatalyst. This study aims to recover and reuse of α-amylase for desizing of cotton via immobilization.

This paper investigates the application of α-amylase immobilized on Chitosan and Eudragit S-100 for cotton fabric desizing. A commercial α-amylase was immobilized on reversibly soluble-insoluble polymers to work out with inherent problems of heterogeneous reaction media. The immobilization process was optimized for maximum conjugate activity, and immobilized amylases were applied for grey cotton fabric desizing.

The desizing performance of immobilized amylases was evaluated in terms of starch removal and was compared to free enzyme. The immobilized amylases showed adequate desizing efficiency up to four cycles of use and were recovered easily at the end of each cycle. The amylase immobilized on Eudragit is more efficient for a particular concentration than chitosan.

Immobilization associates with insolubility and increased size of enzymes which lead to poor interactions and limited diffusion especially in textiles where enzymes have to act on macromolecular substrates (heterogeneous media). The selection of support materials plays a significant role in this constraint.

The commercial α-amylase was covalently immobilized on smart polymers for cotton fabric desizing. The target was to achieve immobilized amylase with maximum conjugate activity and limited constraints. The reversibly soluble-insoluble polymers support provide easy recovery with efficient desizing results in heterogeneous reaction media.

The physical and chemical properties of a new class of synthetic lubricants, the perfluoroalkylpolyether oils and the polytetrufluoroethylene‐thickened greases made from these oils, are described in some detail. The properties which make these products of interest as lubricants for use under severe conditions are shown to be I) excellent thermal and oxidative stability, 2) extreme inertness to many reactive chemicals, 3) broad liquid range and good viscosity‐temperature characteristics, 4) complete nonflammability, 5) good lubricating qualities, 6) compatibility with most elastomers and metals at suitable operating temperatures and 7) insolubility in most common solvents. The commercial process used in the production of these lubricants is described. The oils are disclosed to be fluorine end capped polymers of hexafluoropropylene epoxide having number average molecular weights of from 2000 to 7500, and the preferred thickener for the greases is disclosed to be a telomer of tetrafluoroethylene having a molecular weight of 20,000 to 30,000. A number of the commercial uses of these oils and greases, sold by Du Pont under the trade‐name Krytox®, are described including specific examples of instances where their performance far exceeded that of other available lubricants. Some uses in the space and aircraft industries are also discussed.

The biochemical basis for differences in wheat protein functionality A great deal of research has been carried out to try to determine, in chemical terms, why wheat proteins are so unique from a functional viewpoint. Although some progress has been made, a complete understanding of the molecular properties that are important to the functionality of these proteins is still distant. The reasons for this are that wheat proteins are extremely complex and they are difficult to study, using the more usual techniques of protein chemistry, because of their insolubility except under rather extreme conditions.

Phthalocyanine compounds have their importance due to the massive utilization in various fields. Phthalocyanine blues and greens are used as pigments because of their outstanding stability to light, heat, acids and alkalis, and of course, their insolubility in water and organic solvents. They are used in printing inks, paints and plastics. Phthalocyanines are also used as catalyst in suffer oxidations in the petroleum industry and find use in lasers, medicines, photography, as photo‐ and semiconductors, in xerography and as indicators.

Application of rare earth (RE) salts as a corrosion inhibitor was first proposed by Goldie and McCarrol in 1984. They showed that, with the addition of 0.001 M of Ce(NO₃) or La(NO₃) to 3.5% NaCl solution, the inhibition efficiencies were 91 and 82% for carbon steel, respectively. The aim of this paper is to study the inhibition of a mixture of Ce and La cations on the corrosion prevention of St37 carbon steel in aerated NaCl solutions using weight loss, potentiodynamic polarization, open circuit potential and constant potential measurements.

In this study, St37 steel was used as an experimental sample. The applied inhibitor was a powder mixture of Ce and La oxides with the ratio of Ce/La = 2/1. Each gram of this powder was dissolved in 4 cc acetic acid because of their insolubility in water. Steel samples were polished with 120 to 800 grit SiC polishing papers, deoxidized in 15 per cent HCl, and then ultrasonically cleaned in ethanol. They were degreased in acetone and were dried in a flow of hot air.

It has been shown that a mixture of RE cations (Ce and La) can be used as a corrosion inhibitor for carbon steel in NaCl containing solutions. The optimum inhibitor concentration was found to be 500 ppm with a maximum inhibition efficiency of 76%. An increase in Cl⁻ ion concentration and a rise in temperature from room temperature to 70°C can have an adverse effect on corrosion inhibition efficiency.

The results obtained from various experiments indicated that the mixture of Ce and La cations could be considered as a suitable inhibitor for carbon steel in low to medium chloride‐containing solutions. Owing to their non‐toxic nature, they may be suitable to use in potable water pipelines.

THE technology of lubricant development in this specialised sphere has advanced considerably within the last decade. This is due not only to the more extreme operating temperatures and diverse chemicals handled by this type of valve (necessitating a more critical approach to the formulation of the lubricants used) but also to the many synthetic materials now available which may be used in their compounding.

Life is made up of debits and credits, as Kipling wrote, long accounts have to be paid — mistakes, misconduct, misdeeds, all the mischief and harm they cause, exact payment which has to be met by someone, not necessarily those that cause the trouble; all too often by innocent victims. The recent industrial strife, destruction and violence, despite the plausible excuses for it, will have disastrous results, a colossal debit in the nation's accounts; and the mass of the people, the vulnerable groups including several millions of elderly pensioners, the handicapped and sick, are under no illusions who will have to pay. The posturing defiance — “heads held high”, bands playing martial music — the complete lack of concern or regret for others will make no difference to the overtaking retribution.

This study aims to focus on the main materials used in consolidation processes of illuminated paper manuscripts and leather binding.

For each material, chemical structure, chemical composition, molecular formula, solubility, advantages, disadvantages and its role in treatment process are presented.

This study concluded that carboxy methyl cellulose, hydroxy propyl cellulose, methyl cellulose, cellulose acetate, nanocrystalline cellulose, funori, sturgeon glue, poly vinyl alcohol, chitosan, chitosan nanoparticles (NPs), gelatin, aquazol, paraloid B72 and hydroxyapatite NPs were the most common and important materials used for the consolidation of illuminated paper manuscripts. For the leather bindings, hydroxy propyl cellulose, polyethylene glycol, oligomeric melamine-formaldehyde resin, acrylic wax SC6000, pliantex, paraloid B67 and B72, silicone oil and collagen NPs are the most consolidants used.

Illuminated paper manuscripts with leather binding are considered one of the most important objects in libraries, museums and storehouses. The uncontrolled conditions and other deterioration factors inside the libraries and storehouses lead to degradation of these artifacts. The brittleness, fragility and weakness are considered the most common deterioration aspects of illuminated paper manuscripts and leather binding. Therefore, the consolidation process became vital and important to solve this problem. This study presents the main materials used for consolidation process of illuminated paper manuscripts and leather bindings.

The optimal location of plants by a global firm is analyzed for the first time using measures of distance along the spherical surface of Planet Earth. With a uniform distribution of customers an optimal location strategy will normally seek a space-filling configuration of identical areas that are as near circular as possible. The hexagonal space-filling solution for location on an infinite plane cannot be generalized to the surface of a sphere. Different spatial patterns are required for different numbers of plants; these may be based on triangles, squares, or pentagons. The chapter reviews the current state of knowledge on the topic, drawing on theories of spherical geometry and regular convex polyhedra, and on applications in physics, chemistry, and medicine. Overall, there appears to be no general solution to the problem; only a set of quite different solutions for various special cases. The lack of any general solution to this central problem in international business illustrates the “impossibility” referred to in the title of this chapter.