Synthesis of a fullerene/expanded graphite composite and its lubricating properties

A fullerene/expanded graphite composite, in which fullerene crystals were incorporated into the expanded graphite interspaces, was prepared by chemical and thermal treatments and its lubricating properties in commercial grease were investigated. Expanded graphite, which was synthesized from graphite by oxidizing by KMnO₄ in 98% H₂SO₄ containing NaNO₃ and by heating at 400 °C for 3 min, and fullerene were placed in a stainless steel tube, and were heated in a furnace under vacuum at 600 °C for 2 weeks. The fullerene/expanded graphite composite obtained was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy (SEM). XRD and FT-IR analyses showed that crystalline fullerene was present in the material and SEM images confirmed that it existed in the expanded graphite interspaces. The composite was blended with a commercial grease, and its lubricating properties were investigated using a four-ball lubricant tester. These properties were evaluated by measuring the wear scar diameter and wear volume loss of the test ball. The combination of composite and grease provided a better lubricating performance than that of pure graphite and grease.     

Comparative analysis of starch properties of different root and tuber crops of Sri Lanka

The physicochemical properties of starches of six different root and tuber crop species grown mainly in Sri Lanka showed significant differences among the tested crop species and varieties. The median granule size of starch of tested root and tuber crop species varied from 33.5 to 10.2 μm. The largest granule size and the highest blue value were given by the canna, Buthsarana, and yam species, in that order. The amylose content of cassava was higher than those of sweet potato and many yams. High peak viscosities, high breakdown, and high final viscosities were observed in yams, and, generally, such starch showed a high swelling power. According to the correlation analysis, these pasting properties would mainly be due to their larger starch granule size. Based on the thermal properties, cassava starch showed less energy requirement for gelatinization and thus gelatinized at lower temperatures. Furthermore, a higher susceptibility of raw cassava starch toward fungal glucoamylase was observed. The low enzyme digestibility of raw yam starch would be due to its large granules. Correlation analysis showed that the blue value and starch granule size were important in determining the pasting, thermal, and other properties of starch.     

Kinetics of permeation of nucleotide through oil/water interface in the interaction of nucleotide with octadecylamine and dodecyl guanidine

The transports of tritiated ATP, ADP and AMP from the aqueous to scintillator phase with and without octadecylamine (or dodecyl guanidine) have been studied by the layered scintillation method and a theory suitable for an explanation of the results has been presented. (1) Transport processes were all expressed by the first order kinetics. (2) For the simple partitioning of ATP, the reciprocal of the rate constant of the backward permeation was linear with respect to the square of the partition coefficient. (3) For the transport of nucleotide with chemical reaction, the reciprocal of the rate constant of the backward permeation was linear against the overall partition coefficient of nucleotide. (4) A theory was presented on the basis of a general diffusion equation by assuming the two-film model with potential energy near the interface. (5) The theory could explain the dependences of the permeation rates on the partition coefficients. (6) From the finding that the ratio of the apparent diffusion coefficient in aqueous to scintillator phase was much smaller than unity, the occurrence of an energy barrier at interface was suggested. For the simple partitioning of ATP, the energy barrier was not significant.     

Safety and structural analysis of polymers produced in manufacturing process of alpha-lipoic acid

Alpha-Lipoic acid has recently been permitted for use in foodstuffs and is contained in tablets and capsules. Although alpha-lipoic acid is synthesized from adipic acid, the safety of polymers produced during the purification and drying processes has been an issue of concern. Hence, we examined the safety profiles of thermally denatured polymer (LAP-A) and ethanol-denatured polymer (LAP-B) produced in the manufacturing process of alpha-lipoic acid. Furthermore, we conducted structural analysis of these polymers by 1H-NMR and FAB-MS spectroscopy. In a consecutive ingestion test, male and female mice ingested diet containing 0.1 and 0.2% LAP-A and -B for 4 weeks. Blood uric acid, potassium and lactate dehydrogenase (LDH) tended to increase without dose-dependency. Relative liver weights were also increased. However, male dogs that were orally administered LAP-B (500 mg/kg) once did not show any abnormalities in blood parameters or general condition. These findings indicate that alpha-lipoic acid polymers are not acutely toxic; however, chronic ingestion of these polymers may affect liver and kidney functions.     

Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Catalytic oxidation of biphenyl derivatives was investigated using laccase in a homogeneous aqueous-organic system. A thermostable laccase from Trametes sp. showed the highest catalytic activity for the oxidation of 4-hydroxybiphenyl (4-HB) at a reaction temperature of 60 degrees C when dimethylsulfoxide (DMSO) was employed as a co-solvent. Furthermore, the catalytic performance was successfully enhanced by the incorporation of a laccase mediator system (LMS) into the aqueous-DMSO media. The catalytic performance strongly depended on the type of mediator, and the highest activity was observed with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as mediator, suggesting the importance of the selection of a suitable mediator. It was verified that this mediator system is applicable to the oxidation of several biphenyl derivatives with hydroxyl groups.     

Microencapsulation of bioactive compounds from mulberry (Morus alba L.) leaf extracts by protein–polysaccharide interactions

Mulberry leaf extracts were generated using four concentrations of ethanol (50%, 60%, 70%, and 95% v/v). A 60% ethanolic mulberry leaf extract (60E) yielded a high total phenolic content (TPC) and antioxidant activity using 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging and a ferric reducing antioxidant power (FRAP) assay. Coating materials were derived using a combination of soy protein isolates (SPI) and low methoxyl (LM) pectin in a 1:1 ratio. The effect of various parameters on microencapsulation, such as pH (3.5, 4.0, and 4.5) and the concentration of coating materials (2.5, 5.0 and 7.5% w/v), was studied. Microcapsules produced using 60E as a core material at pH 4.0 with 7.5% of coating material showed a high encapsulation yield, encapsulation efficiency, TPC and antioxidant activity.     

A breakthrough to the plasma deposited dry-developable e-beam resist

This paper presents the preliminary results of efforts to improve dry processed electron beam resist materials using plasma polymerization coating technology. Three approaches investigated were chemical susceptibility modification, the use of multilayer resist structures, and the effect of grafting reactions.     

Molecular, seasonal, and spatial distributions of organic aerosols from fourteen Chinese cities

Organic aerosols were studied at the molecular level in 14 coastal and inland mega-cities in China during winter and summer 2003. They are characterized by the abundant presence of n-alkanes (annual average, 340 ng m(-3)), fatty acids (769 ng m(-3)), sugars (412 ng m(-3)), and phthalates (387 ng m(-3)). In contrast, fatty alcohols, polyols/polyacids, lignin and resin products, sterols, polycyclic aromatic hydrocarbons (PAHs), and hopanes were detected as relatively minor components. n-Alkanes show a weak odd/even carbon predominance (CPI = 1.1) and PAHs show a predominance of benzo(b)fluoranthene, suggesting a serious contribution from fossil fuel (mainly coal) combustion. Their concentrations (except for phthalates and polyols/polyacids) were 2-15 times higher in winter than summer due to a significant usage of coal burning and an enhancement of atmospheric inversion layers. Phthalates were found to be more abundant in summer than winter, probably due to enhanced vaporization from plastics followed by adsorptive deposition on the pre-existing particles. Concentrations of total quantified compounds are extremely high (approximately 10 microg m(-3)) in the midwest (Chongqing and Xi'an) where active industrialization/urbanization is going on. This study shows that concentrations of the compounds detected are 1-3 orders of magnitude higher than those reported from developed countries.