Simulation of carbon nanotube based p-n junction diodes

Taking advantage of the unique characteristics of an ambipolar carbon nanotube field effect transistor (CNTFET), a ‘p-n junction’ is simulated along the single-walled carbon nanotube channel using two separate gates close to the source and drain of the CNTFET, respectively. The current-voltage characteristics of the double-gated CNTFET are calculated using a semiclassical method based on the Schottky barrier field effect transistor mechanism. The calculation results show a good rectification performance of the p-n junction.     

Interfacial pH measurement during the reduction of dissolved oxygen in a submerged impinging jet cell

A pH sensor-grid assembly is used in a submerged impinging jet cell to measure the interfacial pH during the reduction of dissolved oxygen in well controlled flow conditions. Experiments were performed in a 0.5m K2SO4 solution with and without carbonate ions. In each case a good agreement between experiment and theory is found. In particular it was confirmed that, in the absence of chemical reaction and for a totally mass transport controlled oxygen reduction reaction, stirring has no influence on the interfacial pH.     

Quantitative fatty acid analysis of vegetable oils by gas-liquid chromatography

Summary The fatty acid composition of a number of vegetable oils and of two synthetic mixtures of methyl esters are compared by gas-liquid chromatography and by standard methods. The calculated iodine values from G.L.P.C. results are in good agreement with measured iodine values and are indicative of the reliability of the G.L.P.C. values. Standard methods gave lower values for linoleic acid and higher values for linolenic acid than did G.L.P.C. This deviation was particularly evident in oils with a high proportion of linolenic acid,e.g., linseed oil. The results of G.L.P.C. are considered to be accurate to within one unit percentage. Thermal stability of the polyester polymers can be improved by using 1,4-butanediol or ethylene glycol as the polyols instead of diethylene glycol. Issued as N.R.C. No. 5373. Presented at 32nd annual fall meeting, American Oil Chemists' Society, October 20–22, 1958, Chicago, Ill. National Research Council of Canada Postdoctorate Fellow, 1957     

Aspects of moisture kinetics of coal bottom ash in concrete

The moisture kinetics aspects of composite granular material samples composed of natural sand and bottom ash (BA) from thermoelectric power stations and the use of this material in the production of durable concretes, in relation to water transport, are here discussed. The evaluations of the phenomenon of water absorption by capillarity and the loss of water through air drying until hygroscopic equilibrium, were carried out in accordance with classic procedures found in the literature and also newly developed procedures. The results showed that due to the high porosity of BA, the water absorption by capillarity along with the absorption velocity were higher in the compositions with greater BA content. The values for moisture equilibrium from air drying, absorption from capillarity and sorptivity obtained in the hygroscopic equilibrium tests, carried out on the same samples after absorption, were also higher in the samples with BA. These samples also requited a longer drying time.     

Influence of genetics,environment and admixtures on low erucic acid rapeseed in Canada

Single plant isolates in theBrassica napus andBrassica campestris species of rapeseed yielded glyceride oil containing small amounts of erucic acid. Agronomically suitable varieties were grown commercially in 1971 as the first phase in a changeover of Canadian rapeseed production from varieties with erucic contents of 20–45% to low erucic acid varieties. A program to monitor the erucic content by gas chromatographic analysis in the stages of production, handling and transportation from seed to export shipment was undertaken to evaluate the effects of genetics, environment and admixture. The individual increase in erucic content ranged from 0.5 to 1.0, resulting in total increases of 1–2%. NRCC No. 13471. One of six papers presented in the symposium “Rapeseed Marketing and Breeding,” AOCS Meeting, Ottawa, September 1972.     

Preparation of long-chain fatty acid chlorides

Summary A rapid method has been found for preparing the long-chain fatty acid chlorides, which eliminates purification by distillation. It gave a quantitative yield of product containing less than 1.5% free acid. The method involves treating the free acid with phosphorus pentachloride or trichloride in an inert organic solvent and removing the excess chlorinating agent by washing the solvent phase with water. Phosphorus pentachloride and Skellysolve “F” were preferred for laboratory preparations. For commercial purposes however either chlorinating agent could be used in a variety of inert organic solvents. Infrared analysis was found to give a rapid measure of the free acid content of the prepared acid chlorides. Presented at the fall meeting, American Oil Chemists' Society, Philadelphia, Pa., Oct. 10–12, 1955. Issued as N. R. C. No. 4240.     

Retarding effects of DNA on the autoxidation of liposomal suspensions

Deoxyribonucleic acid (DNA) is associated with the cell membrane of prokaryotes and the inner nuclear membrane of eukaryotes. The unsaturated fatty acids of phospholipids, which constitute the bilaminar structure of membranes, undergo autoxidation in the presence of O₂. Calf thymus DNA was incubated with methyl archidonate-enriched phosphatidyl choline liposomes in order to study the effect of DNA upon the oxidation of phospholipids while present in their natural in vivo bilayer configuration. DNA retarded the rate of lipid oxidation and the TBA test, but it did not alter the induction period. These results suggest that DNA is scavenging free radicals produced within the phospholipid bilayer.     

Performance of treated hybrid fiber reinforced-thermoplastic composites under extreme conditions. IV. Use of glass fiber and sawdust as hybrid fiber

The mechanical properties and dimensional stability of hardwood aspen in the form of sawdust and surface-treated glass fiber-polystyrene composites were evaluated under various extreme conditions, e.g., variation in the testing temperature (from +25° to ?20°C), exposure to boiling water and heat in an oven at +105°C. The compatibility of wood fiber with glass fiber and with polystyrene improved by precoating the wood fiber with a coupling agent, e.g., 8% isocyanate, 4% silane and polymer. The mechanical properties of the composites, in particular, treated sawdust/glass fiber-filled composites, increased under extreme conditions in comparison with those filled with nontreated sawdust/glass fiber. Under the same conditions, dimensional stability also supports this observation.     

Characterization of polymer‐layered silicate (clay) nanocomposites by transmission electron microscopy and X‐ray diffraction: A comparative study

Several polymer‐layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide‐angle X‐ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene‐g‐maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d‐spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand‐alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003