Dissolution of perfluoroalkyl oligomers in lubricating oil for enhancing wear resistance and fuel economy

Perfluorobutyl-1,1,2-tri-H-1-hexene and perfluoroalkyl methacrylate have been solubilized in lubricating oil by single-step free radically grafting onto poly(ethylene-co-propylene). Perfluoroalkyl-1,1,2,2-tetra-H-ethanol and perfluoropolyether carboxylic acid were solubilized by condensing with poly[(ethylene-co-propylene)-g-glycidyl methacrylate], generating the corresponding perfluoroalkyl ether or ester, respectively. Solubilization of 1,1,2,2-tetra-H-ethanol was also achieved by condensing with poly[(ethylene-co-propylene)-g-2-isocyanoethyl methacrylate] to the corresponding perfluoroalkyl urethane. Scar diameter reductions ranged from 9.4 to 58% using perfluoro-modified graft copolymers as determined using the Four Ball Wear Test, although optimum reductions were obtained using perfluoroalkyl urethane-modified graft copolymers. Moreover, a semiquantitative correlation of scar reductions and thermal instability was determined. Sequence VI engine testing of perfluoroalkyl urethane graft copolymers containing pendant perfluoroalkyl chain lengths of 8.2 and 7.2 had an Equivalent Fuel Economy Index of 4.33 and 4.27, respectively. © 1994 John Wiley & Sons, Inc.     

Lipids ofCrassostrea virginica. I. Preliminary investigations of aldehyde and phosphorous containing lipids in oyster tissue

Oyster tissue contained 2.4% lipid, 0.14 μmole aldehyde per milligram lipid and at least 10 μg phosphorous per milligram lipid. The neutral lipid represented 58%, the glycolipid 6%, and the polar lipid 36% of the total lipid recovered after silicic acid column chromatography. Aldehydes were found in all fractions, but the presence of plasmalogen was verified in only the neutral and polar lipid fractions. At least 68% of the plasmalogen in oyster lipid was found in the polar lipid fraction. At least 13% of the phosphorous in oyster lipids was present as phosphonolipid. The distribution of phosphate and phosphonate lipids was: diacyl phospholipid 38.1%, plasmalogen phospholipid 21.8%, sphingophosphonolipid 13.5%, glyceryl ether phospholipid 8.3%, sphingophospholipid 6.9%, plasmalogen phosphonolipid 6.4%, diacyl phosphonolipid 2.6%, and glyceryl ether phosphonolipid 2.4%. When the per cent of phosphorous as phosphonolipid within the plasmalogen and glyceryl ether classes was calculated, similar values were obtained. These results support the hypothesis that there is a product precursor relationship between these two classes of lipids. Some of the data taken from a thesis to be submitted to the Graduate School, University of Maryland, by Leslye Johnson in partial fulfillment of the requirements for the M.S. degree in biochemistry.     

Hydrogenation of 3,4-epoxy-1-butene over Cu–Pd/SiO2 catalysts prepared by electroless deposition

Electroless deposition has been used to prepare Cu–Pd/SiO₂ bimetallic catalysts wherein initial Cu coverages are limited only to the pre-existing Pd surface. Cu loading on the Pd surface can be systematically varied by modification of deposition kinetic parameters. In this case deposition time was used as the kinetic variable for the preparation of a series of Cu–Pd catalysts. These materials have been characterized using atomic absorption, CO chemisorption, and FT-IR (adsorption of CO), and then evaluated for the hydrogenation of 3,4-epoxy-1-butene, a functionalized olefin having many potential reaction pathways. Catalyst performance and characterization results suggest that Cu is not distributed in a monodisperse manner on the Pd surface, indicating the existence of autocatalytic deposition of Cu on Cu sites. The FT-IR results suggest that although CO adsorption on all sites is suppressed by Cu addition, initial Cu deposition occurs more readily on certain sites. The bimetallic Cu–Pd sites that are formed exhibit unusually high activity for EpB conversion and formation of unsaturated alcohols and aldehydes. This bimetallic effect on catalyst activity and selectivity is best explained, not by the existence of either ligand or ensemble effects, but rather by the bifunctional nature of the Cu–Pd sites present on the surface of these catalysts.     

Chemical Defense in the Plant Bug Lopidea robiniae (Uhler)

Secretions from the metathoracic glands (MTG) of the black locust bug, Lopidea robiniae (Uhler) (Heteroptera: Miridae) contained six major compounds, including (E)-2-hexenal, (E)-2-hexen-1-ol, (E)-2-octenal, (E)-2-octen-1-ol (E)-2-heptenal, and (Z)-3-octen-1-ol. Males and females did not differ significantly in the relative compositions of identified compounds. In feeding trials, six bird species [robin (Turdus migratorious), blue jay (Cyanocitta cristata), brown thrasher (Toxostoma rufum), killdeer (Charadrius vociferus), starling (Sturnus vulgaris), and house wren (Troglodytes aedon)] demonstrated feeding aversions towards L. robiniae, implying that black locust bugs are chemically defended. Bugs discharged the liquid contents of their MTG when attacked, thereby producing a strong and distinct odor. Some birds immediately ejected bugs out of their mouth after biting them, suggesting that the MTG secretion was a deterrent.     

Catalytic Combustion of Model Carbon Particles (CPs) over Pt/β-SiC Catalyst

Platinum catalyst supported on a medium surface area -SiC was successfully used for the catalytic combustion of model carbon particles and compared to a catalyst supported on a low surface area -SiC. The -SiC-based catalyst showed no deactivation as a function of cycling tests while a strong deactivation was observed on the -SiC-based catalyst. This deactivation was attributed to the progressive encapsulation of the platinum particles by a layer of silica which built up during the combustion cycle. These results render possible the use of Pt/-SiC catalyst as a diesel carbon particle catalytic filter with continuous regeneration.     

Aerodynamics and aerosol particle deaggregation phenomena in model oral-pharyngeal cavities

The results of numerical simulations of the aerodynamics and of solid aerosol deaggregation phenomena arising in the process of airflow through various model human oropharyngeal cavities are reported. Special attention is given to the relevance of these simulations to the inhalation of dry-powder therapeutic aerosols. Several two- and three-dimensional mouth and throat geometries (terminating just beyond the larynx) are considered. Cross-sectional area-averaged viscous stress values are numerically determined as a function of distance from the mouth opening. These values, ranging from approximately 10 to 500 dyn cm⁻², are compared with estimates of Van der Waals attractive forces per unit area of particle-particle contact so as to evaluate the ability of the flowing airstream to deaggregate aerosol particles that enter the mouth in an aggregated state (held together principally by Van der Waals attractive forces). Estimates of airstream viscous stress differ markedly depending on whether the geometry is two- or three-dimensional. Quantitative differences between flow in a 90°-bend model and an oropharyngeal geometry numerically reconstructed from a cast of a human mouth and throat are especially significant in regards to the ability of the airstream to break apart particle agglomerates. For all geometries it is observed that increasingly smaller particle agglomerates may potentially be separated as the airflow rate increases from 30 to 2001 min⁻¹. At the highest airflows, aggregated particles of diameter near to or even below 1 μm may potentially be separated by the airflow. If separation of particle agglomerates is to occur, it appears far more likely to take place in the throat than in the mouth. This is especially apparent for the more physiologically faithful oropharyngeal geometries considered.     

Living carbocationic polymerization

Conventional cationic polymerization can be converted into living carbocationic polymerization (LC^⊕Pzn) by the introduction of common anion into the charge. Thus the conventional polymerization of isobutylene (IB) induced by the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl₄ combination yields LC^⊕Pzn of IB upon the addition of tetrabutyl ammonium chloride (n-Bu₄NCl), most likely due to then-Bu₄NCl+TiCl₄ ?n-Bu₄N^⊕+TiCl ₅ ^⊕ equilibrium. A kinetic model has been developed and tested which corroborates these propositions. By this model we have gained for the first time quantitative insight into the quasiliving equilibrium.     

Interactive sonification to assist children with autism during motor therapeutic interventions

Personal and Ubiquitous Computing - Interactive sonification is an effective tool used to guide individuals when practicing movements. Little research has shown the use of interactive sonification...     

Structural variability and its relation to edaphic attributes of mangroves in the south‐west coast of India

We estimated the tree structural variables (density, frequency and basal area) of true mangroves and soil variables like particle size distribution, carbon, available nitrogen and phosphorus, sulphur, nutrient cations (K, Na, Ca, Mg) of Cochin mangroves and examined the relationship between vegetation and environment. The study sites were classified as seaward fringe, riverine and interior. Of the thirteen true mangrove species present, Avicennia officinalis, Sonneratia caseolaris and Excoecaria agallocha showed higher Importance Value Index. The mean stem density varied from 80 to 25,000 no./ha and basal area from 0.1 to 39.68 m²/ha. Seaward mangroves showed maximum stand basal area and biomass production while riverine exhibited maximum density. Maturity Index value of Cochin mangroves revealed a very low degree of structural maturity. Interior mangroves were characterized by silty soil with higher nutrient concentrations. Principal component analysis of soil data revealed that the major factors influencing mangrove vegetation were soil texture, nutrients, salinity and oxidation–reduction potential. The stem density and basal area of different species correlated highly with soil nutrients and texture (p < .001) while salinity showed negative correlations with vegetation characteristics. The data generated in the study would be fundamental in site‐specific management and conservation efforts of these degrading mangroves.     

A computational approach to characterize formation of a passivation layer in lithium metal anodes

Li metal anode is the “Holy Grail” material of advanced Lithium-ion-batteries (LIBs). However, it is plagued by uncontrollable dendrite growth resulting in poor cycling efficiency and short-circuiting of batteries. This has spurred a plethora of research to understand the underlying mechanism of dendrite formation. While experimental studies suggest that there are complex physical and chemical interactions between heterogeneous solid-electrolyte interphase (SEI) and dendrite growth, most of the studies do not reveal the mechanisms triggering these interactions. To deal with this knowledge gap, we propose a multiscale modeling framework which couples kinetic Monte Carlo and Molecular Dynamics simulations. Specifically, the model has been developed to account for (a) heterogeneous SEI, (b) dendrite-SEI interactions, and (c) effect of electrolyte on Li electrodeposition and potential dendrite formation. This allows the proposed computational model to be extended to various electrolytes and SEI species and generate results consistent with previous experimental studies.