Effect of calendering on paper surface micro-structure: A multi-scale analysis

Paper is a complex composite material. Its structure and surface greatly influence its end use properties. Calendering is a finishing process applied to paper to provide a shiny surface and to improve the smoothness. Hence, the control of the efficiency of calendering and the characterization of the final product necessitate the measure of the surface modification. Furthermore the relationship between the surface and the obtained level of gloss has to be further developed. The main purpose of this study is to describe the modification of the micro-structure at various scales of the paper surface due to the calendering process (under various processing conditions). The characterization of the paper surface was carried out thanks to an optical device allowing the topographic measurement to be taken at various scales. The equipment combines topographical imaging with a high definition camera, allowing measurement on the exact same area of the sample after each pass in the nip. We therefore introduce a new way to perform multi-scale analysis of the paper surface modification based on fractal theory.     

Feasibility of low frequency straight-ray guided wave tomography

Corrosion is a major problem in the petrochemical industry. Corrosion patches are often inaccessible, and the majority of the conventional nondestructive evaluation techniques are compromised. There is therefore a need for a rapid, accurate, long range inspection technique to measure the remaining thickness in corrosion patches. Low frequency Lamb wave tomography is a potentially attractive technique to rapidly evaluate the thickness of large sections of partially accessible structures. This approach has been used in the past to detect the shape of defects in a range of applications. Time-of-flight straight-ray tomography relies on the dispersive nature of a guided wave mode to reconstruct the depth profile of a corrosion patch. If the frequency is limited to below the cut-off of the higher order modes the interpretation of the signals and the time-of-flight measurement are easier. In order to reconstruct a thickness map with time-of-flight straight-ray tomography the ray theory needs to be valid. There are two validity criteria: the characteristic size of the defect must be larger than the wavelength and larger than the width of the Fresnel zone. For realistic defect sizes, the likely points of operation in the low frequency regime respect the wavelength condition but not the more stringent Fresnel zone condition. The paper demonstrates, with finite element simulations and experiments, that the ray theory criteria cannot be relaxed for low frequency Lamb wave tomography to evaluate the maximum depth of corrosion patch in typical pipe inspection problems.     

Shape Selective Chemistries with Modified Mordenite Zeolites

This is a review of work carried at Dow Chemical on the design and characterization of novel mordenite catalysts with a unique micro and meso-porous structure characterized by a variety of methods including, TEM, BET surface area and pore size distribution, and n-decane hydro-conversion. The catalytic performance of these catalysts in shape selective reactions is illustrated with results from n-decane hydro-conversion and applications to alkylation and trans-alkylation reactions of mono and polynuclear aromatic hydrocarbons and other chemistries. Juan M. Garcés and G. John Lee both retired from The Dow Chemical Company.     

Moisture barrier and physical properties of acetylated derivatives with increasing acetylation degree

Four acetostearin products with increasing acetylation degree were synthesized by chemical interesterification followed by fractionation/blending stages. Their physical properties and functional barrier properties were studied and compared to the properties of technical tristearin. Increasing acetylation degree (AD) modified the triacylglycerols crystal habits and probably led to an increase in acyl chain fluidity, which induced, at macroscopic levels, a decrease in solid fat content (SFC), in melting point, in surface and bulk material hydrophobicity, and an increased moisture effective diffusivity. Water vapor permeability (WVP) coefficients of the materials were partially influenced by the AD factor, but also by the development of macroscopic cracks in lipids presenting high SFC. Acetylated stearin up to 47% (acetyl mol/mol of esterified chain) presented the lowest WVP at 20 °C resulting from an adequate balance between hydrophobicity and mechanical properties of the material.     

Synthesis and characterization of poly([3,4,c]furano-1-germa-1,1-dimethylcyclopentane)

Summary Poly([3,4,c]furano-1-germa-1,1-dimethylcyclopentane) (I) has been prepared by the anionic ring opening polymerization of 3-oxa-7,7-dimethyl-7-germabicyclo[3.3.0]- octa-1,4-diene (II) co-catalyzed byn-butyllithium and HMPA in THF. I has been characterized by¹H,¹³C NMR, IR and UV spectroscopy as well as by elemental analysis. The molecular weight distribution of I has been determined by gel permeation chromatography (GPC), its thermal stability established by thermogravimetric analysis (TGA) and its glass transition temperature (T_g) measured by differential scanning calorimetry (DSC).     

Immunoregulatory functions of paf-acether. VI. Dual effect on human B cell proliferation

The role of paf-acether (paf), a phospholipid cytokine, in the modulation of human B cell function was investigated. Paf, from 1×10⁻⁵ M to 10⁻⁶ M, decreased B cell proliferation induced by both phorbol myristate acetate (PMA) and anti-IgM antibodies (anti-IgM Ab). By contrast, 1×10⁻⁷ M to 1×10⁻⁹ M paf enhanced PMA triggered, but not anti-IgM triggered B cell proliferation. B cell proliferation was modulated between 24 and 72 hr of culture indicating that the effect of paf did not merely reflect a shift in proliferation kinetics. Interestingly, paf also enhanced the spontaneous proliferation of a Burkitt lymphoma-derived B cell line, Raji, which suggests that paf can directly act on B cells. The modulatory effect of paf on peripheral blood B cells was independent of PMA concentration, yet the effect on Raji cells was dependent upon cell density. The data suggest that paf is a potent modulator of B cell function, and may be involved in the control of humoral immune response. Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.     

Arachidonic acid autoxidation in an aqueous media effect of α-tocopherol,cysteine and nucleic acids

The autoxidation of arachidonic acid dispersed in aqueous media was evaluated simultaneously with and without different agents, e.g., α-tocopherol at different concentrations, cysteine, DNA and RNA. The autoxidation rate of arachidonic acid was evaluated by quantitative gas liquid chromatography (GLC) determination of the unoxidized acid and by spectrophotometric measurement of conjugated dienes. α-Tocopherol exhibited a prooxidant activity at concentrations of 1.25 × 10⁻⁴ M and 1.25 × 10⁻⁵ M and a weak antioxidant activity at a concentration of 1.25 × 10⁻⁶ M. Cysteine showed antioxidant activity and greatly reduced the prooxidant activity of α-tocopherol. DNA and RNA had no effect in either case. α-Tocopherol oxidation was followed by high pressure liquid chromatography (HPLC). The prooxidant effect was accompanied by a rapid oxidation of α-tocopherol, except in the presence of cysteine, which prevented the oxidation of α-tocopherol.     

Complete separation of phospholipids from human heart combining two HPLC methods

The separation of phospholipid classes from human heart was achieved in two steps by high performance liquid chromatography (HPLC) using a silica column with an ultraviolet spectromonitor at 206 nm. A complete partitioning of phosphatidylcholines (PC), phosphatidylethanolamines (PE), phosphatidylinositols (PI), phosphatidylserines (PS), cardiolipins (CL), lysophosphatidylcholines (LPC) and sphingomyelins (Sph) was obtained for further analysis.