Phosphorus,Potassium and Leucaena Pruning Interactions on Corn in Haiti

Few P and K fertility studies have been conducted on Haitian soils. Alley cropping is promoted in Haiti but has not been studied in relation to P and K fertility. The effects of P and K fertilizer and leucaena (Leucaena leucocephala (Lam) De Witt) pruning mulch applications on corn (Zea mays L.) were assessed in field experiments on Rhodudalfs over limestone at Salagnac, Lithic Hapludolls over limestone at Bergeau and Typic Hapludalfs over basalt at St. Georges, Haiti. Complete block designs arranged in incomplete factorials of P and K rates were carried out during three seasons. Additional treatments consisted of 30 Mg ha⁻¹ of leucaena prunings applied with and without 60 kg P and 40 kg K ha⁻¹. Grain yield and net income were analyzed and a surface response curve was fitted on treatments without pruning applications. The soils differed markedly in response to P and K with significant PXK interactions. Without leucaena prunings, response surface analysis predicted maximum yields with applications of 95–117 kg P ha⁻¹ and 51–72 kg K ha⁻¹ and maximum net returns with applications of 0.22–89 kg P ha⁻¹ and 43–79 kg K ha⁻¹. Leucaena pruning applications increased yield at all sites. Highest net income was obtained at Salagnac and St. Georges with leucaena prunings applied with P and K, at Bergeau with prunings applied without P and K, suggesting that alley cropping with judicial fertilizer use is a good economic alternative for low resource farmers. Soil parent material and mineralogy should be considered in making fertilizer recommendations.     

Galacto-Oligosaccharide Supplementation Modulates Pathogen-Commensal Competition between Streptococcus agalactiae and Streptococcus salivarius

The members of the infant microbiome are governed by feeding method (breastmilk vs. formula). Regardless of the source of nutrition, a competitive growth advantage can be provided to commensals through prebiotics – either human milk oligosaccharides (HMOs) or plant oligosaccharides that are supplemented into formula. To characterize how prebiotics modulate commensal – pathogen interactions, we have designed and studied a minimal microbiome where a pathogen, Streptococcus agalactiae engages with a commensal, Streptococcus salivarius. We discovered that while S. agalactiae suppresses the growth of S. salivarius via increased lactic acid production, galacto-oligosaccharides (GOS) supplementation reverses the effect. This result has major implications in characterizing how single species survive in the gut, what niche they occupy, and how they engage with other community members.     

Effect of size and density on the thermodynamic predictions of coal particle phase formation during coal gasification

When coal is ground for use in a gasifier, the resulting particles will vary in physical and chemical make-up, in particular, the mineral amount and composition. The resulting ash composition distribution, by particle size and density, of ground Pittsburgh Seam coal was determined. The thermodynamically stable phases were calculated for each particle classification for a range of temperatures, with attention paid to the form of the non-slag phases, which must dissolve in the slag layer on the gasifier wall. Undissolved particles can be carried with the gas, resulting in fouling of downstream components. Results are separated into a comparison of the liquid versus solid phases formed, and a comparison of the phases formed for each particle type. Certain particle compositions form stable crystalline oxide phases that are usually incorporated into the slag at higher temperatures, while others can form metallic iron, which is stable even at high temperatures.     

Radiation tolerance in polymeric dielectrics by small molecule doping, Part II: Thermodynamic and kinetic parameters

The doping of Mylar^® film (composed of semicrystalline poly(ethylene terephthalate)) with small molecule electron traps results in a high-quality dielectric film with excellent radiation tolerance. Fluorenones with electron-withdrawing substituents, doped from ethylene glycol, are excellent candidates to provide this radiation tolerance. Utilizing theories for diffusion and partitioning, this paper extracts kinetic and thermodynamic information from the doping process. Diffusion is significantly retarded, and partitioning significantly enhanced, upon the addition of polar substituents to the dopant molecule; dopant size has a minor impact. Diffusivity corrections due to tortuous paths around the crystallites are accounted for. Additionally, it was found that the solubility parameters, in combination with estimations for the local interaction volumes, provide an excellent method to predict trends in the equilibrium doping behavior via the χ parameter and hydrogen bonding-modified Flory-Huggins theory. Based on this method, estimations are given for the number of hydrogen bonds between ethylene glycol and dopant molecules.     

Conditions for entrainment into a FeOx containing slag for a carbon-containing particle in an entrained coal gasifier

When incompletely gasified coal particles impact the slag layer in an entrained slagging gasifier, a situation will arise where the particles will either get engulfed by the slag or re-entrained into the circulating gas. This will be determined by a balance of forces acting on the particle which in turn is governed by the slag and particle properties, and pertinent gasifier conditions, namely temperature, and particle impact velocity. In this paper a model is introduced that takes into account, the drag-, capillary-, and added mass-forces and predicts the behavior of spherical particles of different sizes and slags of different FeO_x contents. The model predicts that particles either get completely submerged, settle at an incompletely separated position, or oscillate at the interface. A sensitivity analysis was performed showing that for a particle of certain size and impact velocity, submersion is most strongly promoted by a low slag viscosity (largely influenced by FeO_x content) and contact angle (determined by whether or not-reactive wetting and liquid Fe formation occurs).     

The Interaction of the Amylose-Extender and Waxy Mutants of Maize (Zea Mays L.) Fine Structure of Amylose-Extender Waxy Starch

Investigations into the nature of the effect of the amylose-extender (ae) mutant of maize (Zea mays L.) on amylopectin structure were conducted by studying the fine structure of amylose-extender waxy (ae wx) starch. Approximately 59.6% of the starch from ae wx endosperms was converted to maltose by β-amylase. This starch contained 21% apparent amylose and had a λmax of 580 for the iodine-starch complex. Fractionation of ae wx starch on Sepharose 4B-200 gave an elution profile with a single peak characteristic of amylopectin. From these observations we concluded that ae wx starch consisted of an altered amylopectin, with iodine binding properties such that an apparent amylose content of 21% was measured. The fine structures of ae wx and waxy (wx) starches were determined. Pullulanase-debranched chains of whole starches and β-limit dextrins were fractionated by gel permeation. The amylopectin of ae wx was shown to be a loosely branched amylopectin with an average internal chain length of 52 glucose units compared with a length of 30 glucose units for wx. The ae wx outer chains were longer than those of wx and fewer in number per mg of starch. These characterizations demonstrate that ae wx starch has a unique structure which is similar to the anomalous amylopectin reported in ae starch.