Apparatus for measuring physical adsorption on intact supported porous membranes

We present a non-destructive, reusable apparatus with which to measure physical adsorption isotherms of intact porous membranes. We developed a two-piece sample container to make reliable sorption measurements of porous membranes, the properties of which may differ from those of powders due to crystal intergrowth. This novel system employs a resealable container that can be immersed in a cryogenic bath, into which tubular, planar, or other porous membranes and films may be placed. Detailed sorption isotherms, including high-resolution adsorption in the low pressure (micropore-filling) region, are shown for MFI-type zeolite membranes grown on two types and configurations of α-alumina support.     

Fraktionierung und Charakterisierung von ungehärteten Epoxidharzen aus Bisphenol A und Epichlorhydrin

Gel permeation chromatography and thin layer chromatography have been used respectively to separate and characterize the first seven members of an epoxy resin polymer homologous series on a preparative and analytical scale. The epoxy resin was formed by the reaction between Bisphenol-A and epichlorhydrin. NMR was used to identify the oligomers. The relationship between extinction coefficient and degree of polymerisation was also determined.     

Field bioassay ofexo- andendo-brevicomin withDendroctonus ponderosae in lodgepole pine

Bothexo- andendo-brevicomin reduced the response of flyingDendroctonus ponderosae (Coleoptera: Scolytidae) to an attractant composed oftrans-verbenol and terpenes or oftrans- andcis-verbenol and terpenes in a stand ofPinus contorta var.murrayana. These data suggest that racemicexo- andendo-brevicomin may interrupt aggregation in populations of mountain pine beetle colonizing lodgepole pine; functions of the natural chiral compounds are unknown.Research supported by NSF grants DEB 77-11367 and PCN 79-21708 and the O.S.U. School of Forestry. O.S.U. Agric. Exp. Sta. Tech. Paper No. 5713.     

Engineering a pharmacologically superior form of leptin for the treatment of obesity

Leptin plays a central role in the homeostasis of body weight through its regulatory effects on appetite and energy expenditure, yet in trials as a therapeutic agent for the treatment of obesity in humans it has been disappointing. The poor clinical efficacy of leptin results from its short circulating half-life, low potency and poor solubility, necessitating large and frequent doses to obtain even modest clinical benefit. Engineered Fc-leptin immunofusins, consisting of the Fc fragment of an immunoglobulin gamma chain followed by leptin, exhibit improved pharmacological properties with very consistent and potent biological activities. Furthermore, in extending the circulating half-life of the protein in vivo from a few minutes for leptin to many hours for Fc-leptin, these proteins have the potential to reduce drastically the dosage and frequency of administration required to obtain clinical benefit. The results of this study show that the engineered leptin immunofusins described here have significantly enhanced pharmacological properties in comparison with the recombinant leptin that was used in clinical trials. As such, they could represent an important step towards a therapeutically superior form of leptin if the disappointing performance of leptin in early clinical trials was due to its poor pharmacological properties rather than any conceptual weakness in the strategy of using leptin for the treatment of obesity and its related disorders.     

Synergic influence of a surfactant and ultrasonication on the preparation of soluble,conducting polydiphenylamine/silica‐nanoparticle composites

Conducting polydiphenylamine was used to encapsulate silica nanoparticles through the oxidative polymerization of diphenylamine in the presence of ultrasonic irradiation. The polymerization was performed in the presence of sodium lauryl sulfate as a surfactant. Experiments performed in the absence of ultrasound clearly demonstrated that the application of ultrasonication played multiple roles in the preparation of a composite of polydiphenylamine with silica nanoparticles. Ultrasonication dispersed the silica nanoparticles, converted sodium lauryl sulfate to lauryl alcohol, and augmented the dispersion of the silica‐nanoparticle/polydiphenylamine composite in an organic medium. Silica‐nanoparticle/polydiphenylamine composites were also prepared in the absence of ultrasound and/or sodium lauryl sulfate. The silica‐nanoparticle/polydiphenylamine composites were characterized with Fourier trans form infrared spectroscopy, ultraviolet–visible/near‐infrared spectroscopy, and thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3912–3918, 2006     

Kinetic parameters estimation for cure reaction of epoxy based vinyl ester resin

A new graphical estimation technique is proposed for the determination of the kinetic parameters describing an autocatalytic reaction. A differential scanning calorimeter was used to monitor the reaction kinetics of an epoxy-based vinyl ester resin. The method utilizes information from a zero initial reaction rate, conversation at vitrification, the ratio of reaction rate constants under different isothermal conditions, and characteristics of the phenomenological kinetic model with assumptions being made about the overall reaction order. By fitting data to the integrated reaction rate equation with adjustments for the isothermal conditions, the kinetic parameters are estimated without using a linear or nonlinear regression method. Different kinetic parameters can be estimated from data before and after the gel point which was obtained from the relationship between the glass transition temperature and the degree of cure.     

Effect of La/K A-site Substitutions on the Ordering of Ba(Zn1/3Ta2/3)O3

The 1/3 <111>-type ordering of Ba(Zn_1/3Ta_2/3)O₃ (BZT) can be transformed to 1/2 <111>–type ordering by substituting the La³⁺ cation into the A site. The 1/3 <111> ordering in BZT is shown to be reduced, discontinued, and then replaced by 1/2 <111> ordering, using X–ray diffraction, electron microscopy, and Raman spectroscopy. On the other hand, potassium–substituted BZT only displays a reduction in the degree of ordering.     

Oxygen evolution and hypochlorite production on Ru-Pt binary oxides

The electrocatalytic activities of Ru-Pt binary oxide electrodes prepared by thermal decomposition for both oxygen and chlorine evolution reactions (OER and CER) were investigated by cyclic voltammetry (CV) and log i/E relationships (Tafel study). Both CV and Tafel studies revealed that the electrodes from the coating solutions with 60 and 20 mol % Pt content possessed the maximum apparent activity for OER and optimal apparent activity for CER/hypochlorite production, respectively. The specific activity (i/q ^*) revealed that mixing of the RuO₂ and PtO _x had no synergistic effects for OER due to the occurrence of phase segregation, which was revealed by element mapping/surface morphologies and Auger electron spectroscopy. Lower current efficiencies for hypochlorite production were found on the freshly prepared binary electrodes (type I electrodes) than on those having been treated by repetitive CVs (type II electrodes). Stability testing of both type I and II electrodes was measured in 0.5 m NaCl solution at 300 mA cm^–2 for 480 h, indicating that both type I and II electrodes are quite stable under the above conditions.     

Comparative reactivities of coal asphaltenes during hydropyrolysis

Comparisons have been drawn in the relative reactivities of three coal asphaltenes during hydropyrolysis. All were derived from hydrogen donor-solvent extracts of bituminous coal, but had different hydrotreatment histories and different carbon contents (87.1, 91.9 and 90.8 wt% for asphaltenes 1, 2 and 3, respectively). The hydropyrolyses were carried out in the presence of CoO–MoO₃ catalyst and gaseous hydrogen at 8.7 MPa. For two of the asphaltenes (1 and 2) systematic comparisons were made for different reaction times at 425°C; for all three asphaltenes comparisons were made for l h of hydropyrolysis at 425°C. The general pattern of asphaltenes conversion indicated that more pentane-soluble product was produced from asphaltene isolated from straight coal extract (asphaltene 1). For the asphaltenes isolated from hydrotreated extracts, the extent of conversion to liquids was limited when the carbon content was high (asphaltene 2) although the pattern of conversion was similar in the other hydrotreated asphaltene (asphaltene 3). The aliphatic content of the liquid products formed was low, and the distribution of hydrogenated species in the highly aromatic liquid products indicated that complete hydrogenation of the polyaromatics produced in pyrolysis is difficult. Altogether the aliphatics made up ≈ 10 wt% of the asphaltene 1 hydropyrolysate. Aromatic hydrocarbons made up 90% of the liquid product. Phenanthrene, pyrene and anthracene were prominent, and the largest component in the mixture was phenanthrene which, together with other polyaromatics such as fluoroanthene, dominated the liquid product.     

Persistence of nonprotein seed amino acid s-(β-carboxyethyl)-cysteine in young leaves ofCalliandra rubescens Ecological implications

The insecticidal nonprotein amino acid S-(-carboxyethyl)-cysteine (S-CEC) is the major free amino acid in the seeds of severalCalliandra spp. where it accounts for up to 2.9 % of dry weight. Lesser amounts of other related S-containing amino acids and an array of nonprotein imino acids derived from pipecolic acid are other constituents. High concentrations of imino acids, which also show insecticidal activity, are maintained in the mature leaves, but sulfur compounds are lacking. In this study the disappearance of S-CEC from the germinating seeds and young seedlings ofC. rubescens was monitored over time. After 10 weeks, S-CEC continues to be found in high concentrations in the stems and new leaves. As young leaves mature, sulfur compounds quickly decrease in concentration. Traces of S-CEC are found in new leaves of plants up to nine months after germination. Whether high concentration of S-CEC in young leaves is due to transportation from the seed or de novo synthesis is unclear. The ecological implications are discussed.