Model representation of secondary organic aerosol in CMAQv4.7

Numerous scientific upgrades to the representation of secondary organic aerosol (SOA) are incorporated into the Community Multiscale Air Quality (CMAQ) modeling system. Additions include several recently identified SOA precursors: benzene, isoprene, and sesquiterpenes; and pathways: in-cloud oxidation of glyoxal and methylglyoxal, particle-phase oligomerization, and acid enhancement of isoprene SOA. NO(x)-dependent aromatic SOA yields are also added along with new empirical measurements of the enthalpies of vaporization and organic mass-to-carbon ratios. For the first time, these SOA precursors, pathways and empirical parameters are included simultaneously in an air quality model for an annual simulation spanning the continental U.S. Comparisons of CMAQ-modeled secondary organic carbon (OC(sec)) with semiempirical estimates screened from 165 routine monitoring sites across the U.S. indicate the new SOA module substantially improves model performance. The most notable improvement occurs in the central and southeastern U.S. where the regionally averaged temporal correlations (r) between modeled and semiempirical OC(sec) increase from 0.5 to 0.8 and 0.3 to 0.8, respectively, when the new SOA module is employed. Wintertime OC(sec) results improve in all regions of the continental U.S. and the seasonal and regional patterns of biogenic SOA are better represented.     

Physico‐chemical characterization of date varieties using multivariate analysis

BACKGROUND: The fruit of date palm is consumed as an ideal high‐energy food. It is also used for the treatment of colds, fever, liver and abdominal troubles. Its nutritional composition strongly depends upon variety and ripening stage. A number of varieties are available in Pakistan but little is known about their composition and nutritional characteristics. Inherent moisture, volatile matter, ash, fixed carbon, sugar and mineral metals of seven commercial date varieties (Aseel, Basra, Begun, Janshoor, Mazoee, Rabee and Zaidi) were investigated. The physical and chemical compositions with respect to maturation were also monitored for the Aseel variety. RESULTS: The results showed significant varietal differences in moisture, ash and mineral metal composition when analysis of means was conducted at an alpha level of 0.05. The difference between means was insignificant (P > 0.05) for volatile matter, glucose, fructose and total reducing sugars. All varieties were found to be an excellent source of total reducing sugar (78%), potassium (403–632 mg per 100 g) and calcium (27.41–81.47 mg per 100 g). A gradual increase in total reducing sugar and minerals, especially potassium and copper, was observed with maturation. Variety Aseel was grouped on the basis of maturation using principal component analysis. Local date varieties were separated with 48.63% level of similarity from Iranian variety (29.17%) using Cluster analysis. CONCLUSION: This study provides an overview of the physico‐chemical properties of date varieties. The sample varieties showed significant differences except for sugar and volatile matter. Multivariate analysis was found to be an important statistical tool for the separation of samples on the basis of geographical origin and maturations. Copyright © 2008 Society of Chemical Industry     

Evaluation of the Chiral DIANANE Backbone as Ligand for Organolithium Reagents

Novel endo,endo‐2,5‐diaminonorbonane‐derived tertiary C₂‐symmetrical diamines were synthesized via the one‐pot reductive amination of enantiomerically pure norbornane‐2,5‐dione. These ligands were applied to various catalytic reactions such as asymmetric deprotonation, asymmetric bromine‐lithium exchange, and enantioselective addition of aryl‐ and allkylithium reagents to aromatic aldimines.     

Investigation of nanostructure and properties of aromatic–aliphatic polyamide‐based nanocomposites with clay additives

Aromatic–aliphatic polyamide/clay nanocomposites were produced using solution intercalation technique. Surface modification of the clay was performed with ammonium salt of aromatic diamine and the polyamide chains were produced by condensation of 4‐aminophenyl sulfone with sebacoyl chloride (SCC) in dimethyl acetamide. Carbonyl chloride endcapped polymer chains were prepared by adding extra SCC near the end of polymerization reaction. The nanocomposites were investigated for organoclay dispersion, water absorption, mechanical, and thermal properties. Formation of delaminated and intercalated nanostructures was confirmed by X‐ray diffraction and TEM studies. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (8 wt %). Thermal stability and glass transition temperatures of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. The amount of water uptake for these materials decreased as compared with the neat polyamide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Batch-mode micropatterning of carbon nanotube forests using UV-LIGA assisted micro-electro-discharge machining

This paper reports batch-mode, three-dimensional micropatterning for arrays of vertically aligned carbon nanotubes, also known as CNT forests, based on dry micro-electro-discharge machining (μEDM). The process employs an array of copper electrodes microfabricated through an advanced UV-LIGA process enabled with a new photoresist system in combination with electroplating, providing a low-cost path to constructing high-density arrays of μEDM electrodes for high-throughput parallel processing. The fabricated arrays of 85-μm-tall electrodes are utilized to demonstrate and characterize planar dry μEDM for post-growth patterning of CNT forests in air. Die sinking and scanning processes are tested to show pattern transfers with a 4-μm tolerance and an average surface roughness of 230 nm. An elemental analysis suggests that contamination of the electrode material on the produced patterns is minimal. Key characteristics in the use of planar electrodes for batch processing of CNT forests are revealed through experimental analysis and discussed in detail. The results suggest that the investigated process is a promising approach toward offering a cost-effective manufacturing technology for future products functionalized with custom-designed microstructures of CNT forests.     

Synthesis and Characterization of Aromatic–Aliphatic Polyamide Nanocomposite Films Incorporating a Thermally Stable Organoclay

Nanocomposites were synthesized from reactive thermally stable montmorillonite and aromatic–aliphatic polyamide obtained from 4-aminophenyl sulfone and sebacoyl chloride. Carbonyl chloride terminal chain ends were generated using 1% extra sebacoyl chloride that could interact chemically with the organoclay. The distribution of clay in the nanocomposites was investigated by XRD, SEM, and TEM. Mechanical and thermal properties of these materials were monitored using tensile testing, TGA, and DSC. The results revealed delaminated and intercalated nanostructures leading to improved tensile strength and modulus up to 6 wt% addition of organoclay. The elongation at break and toughness of the nanocomposites decreased with increasing clay contents. The nanocomposites were thermally stable in the range 400–450 °C. The glass transition temperature increased relative to the neat polyamide due to the interfacial interactions between the two phases. Water uptake of the hybrids decreased upon the addition of organoclay depicting reduced permeability.     

Effects of varying forage and concentrate carbohydrates on nutrient digestibilities and milk production by dairy cows.

Five Holstein cows with ruminal cannulas were used in a 5 x 5 Latin square design to determine the effect of replacing forage NDF with soyhull NDF and varying concentrations of nonstructural carbohydrates on nutrient digestion and milk production. Diets in which NDF percentage from forage (corn silage: alfalfa hay, 1:1) was 80 (control), 70, or 60 were formulated by substituting soyhulls for forage; total forage was 43.2, 36.7, and 31.1% of the diets, respectively, but total NDF was 31%. Nonstructural carbohydrates were formulated to be 47 (control), 35, or 25% by substituting soyhulls, roasted soybeans, and Ca soaps for concentrate. Ruminal acetate: propionate ratio decreased linearly when diets lower in forage NDF were fed, but it increased quadratically when dietary nonstructural carbohydrates were reduced. Apparent digestibility of OM increased quadratically, but NDF digestibility and lactation performance were unaffected when diets lower in forage NDF were fed. Digestibility of NDF increased linearly when nonstructural carbohydrates were reduced, perhaps because of greater digestibility of soyhull NDF and smaller negative associative effects. Fat from soybeans and Ca soaps was increased as nonstructural carbohydrates decreased. Added fat probably increased fatty acid digestibility and decreased milk protein percentage. Greater FCM production without correspondingly greater feed intake or BW loss increased feed efficiency as nonstructural carbohydrates decreased. In dairy rations containing soyhulls, 60% of dietary NDF from forage should maintain lactation performance, and decreasing nonstructural carbohydrates to 25 to 35% of feed DM, coupled with adding dietary fat, may decrease negative associative effects and improve efficiency of milk production.