Novel poly(ester-urethane)s were prepared by a synthetic route using a lipase that avoids the use of hazardous diisocyanate. The urethane linkage was formed by the reaction of phenyl carbonate with amino acids and amino alcohols that produced urethane-containing diacids and hydroxy acids, respectively. The urethane diacid underwent polymerization with polyethylene glycol and α,ω-alkanediols and...

current world conditions require compressors to be both efficient and economical to manufacture. one means of improving efficiency in a rotary vane (or any) compressor is to use the lubricant as a heat transfer agent. A rotary vane refrigerator compressor was modified and instrumented for calorimeter testing so that the performance improvement could be identified. The changes and testing were c...

Abstract The tribological behavior of oil-in-water emulsions formulated with natural lyotropic liquid crystal (LLC) emulsifiers based on sucrose ester was studied for the first time. Polarized optical microscopy, synchrotron radiation small-angle X-ray scattering, wide-angle and infrared microspectroscopy demonstrated that LLC were tightly ordered at oil—water interface a distinct nematic textu...

We review some of the key tribological issues of relevance to motorsport applications. Tribology is the science of friction and wear, and in a high performance engine, friction and wear are controlled by good component design (e.g. the engine and the transmission) and also by the use of high performance lubricants with the correct physical (and chemical) properties, matched to the machine they ...

The synovial fluid (SF) of joints normally functions as a biological lubricant, providing low-friction and low-wear properties to articulating cartilage surfaces through the putative contributions of proteoglycan 4 (PRG4), hyaluronic acid (HA), and surface active phospholipids (SAPL). These lubricants are secreted by chondrocytes in articular cartilage and synoviocytes in synovium, and concentr...

The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant on binary direct compression mixtures. Magnesium stearate (MGST), stearic acid (STAC), glyceryl behenate (COMP) and hexagonal boron nitride (HBN) were tested. The binary mixtures were 1:1 combinations of spray dried lactose (FlowLac 100), dicalcium phosphate dihydrate (Emcom...

We construct a computer code to solve the (Nosé Hoover) finite-temperature classical dynamics of a Lennard-Jones solid lubricant slab between two rigid solid substrates. The code is based on a standard periodically repeated supercell scheme, which imposes relative substrates/lubricant densities. We investigate the possible occurrence of Moiré patterns due to incommensurability, and for the drag...

Here we describe a 5-step sequence to prepare the AB enone 1, the key precursor to fully synthetic tetracyclines, that begins with a diastereoselective Michael-Claisen coupling of two simple starting materials, a cyclohexenone (compound 2 or, in a refinement, a substituted variant, vide infra) and the isoxazole ester 3. This advance defines an 8-step linear sequence to 6-deoxytetracycline antib...

Although biotin is an essential enzyme cofactor found in all three domains of life, our knowledge of its biosynthesis remains fragmentary. Most of the carbon atoms of biotin are derived from pimelic acid, a seven-carbon dicarboxylic acid, but the mechanism whereby this intermediate is assembled remains unknown. Genetic analysis in Escherichia coli identified only two genes of unknown function r...

Corn starch particles are used as a surgical glove lubricant. At present there is no better alternative for this lubricant. Implantation of corn starch particles into the peritoneal cavity can induce foreign body reactions, starch peritonitis and starch granulomata, and may cause adhesions and intestinal obstruction. Starch peritonitis should be treated conservatively.