Establishment of trees on minesoils during drought and wet years

ABSTRACT

In two studies, green ash (Fraxinus pennsylvanica) and white pine (Pinus strobus) were planted on three minesoils (graded topsoil, ripped topsoil, and gray cast overburden). Mixtures of grasses and/or legumes were seeded at different times in relation to tree planting. In the first study, tree planting was followed by several weeks of drought; in the second study, precipitation was above average for the first two growing seasons following planting. In the drought year, survival of green ash was influenced by minesoil type, herbaceous mixture, and herbaceous seeding time in relation to tree planting. Among minesoils, mean survival was highest (87%) on cast overburden. Seeding grasses the fall before planting resulted in poor ash survival (40% to 47%) compared with seeding at time of planting (82% to 85 %). Ash survived well (81 % to 94%) on legume-seeded plots. When tree planting was followed by two wet seasons, survival at 4 and 5 yr ranged from very good to excellent in all treatments. Total height of ash trees on cast overburden averaged 31 % less than that of trees on topsoil, and 29% greater on legume-seeded subplots than trees on grass subplots, although herbaceous biomass was greater on legume subplots. The three minesoils proved unsuitable for white pine.     

Cellular Association and Assembly of a Multistage Delivery System

The realization that blood‐borne delivery systems must overcome a multiplicity of biological barriers has led to the fabrication of a multistage delivery system (MDS) designed to temporally release successive stages of particles or agents to conquer sequential barriers, with the goal of enhancing delivery of therapeutic and diagnostic agents to the target site. In its simplest form, the MDS comprises stage‐one porous silicon microparticles that function as carriers of second‐stage nanoparticles. Cellular uptake of nontargeted discoidal silicon microparticles by macrophages is confirmed by electron and atomic force microscopy (AFM). Using superparamagnetic iron oxide nanoparticles (SPIONs) as a model of secondary nanoparticles, successful loading of the porous matrix of silicon microparticles is achieved, and retention of the nanoparticles is enhanced by aminosilylation of the loaded microparticles with 3‐aminopropyltriethoxysilane. The impact of silane concentration and reaction time on the nature of the silane polymer on porous silicon is investigated by AFM and X‐ray photoelectron microscopy. Tissue samples from mice intravenously administered the MDS support co‐localization of silicon microparticles and SPIONs across various tissues with enhanced SPION release in spleen, compared to liver and lungs, and enhanced retention of SPIONs following silane capping of the MDS. Phantom models of the SPION‐loaded MDS display negative contrast in magnetic resonance images. In addition to forming a cap over the silicon pores, the silane polymer provides free amines for antibody conjugation to the microparticles, with both VEGFR‐2‐ and PECAM‐specific antibodies leading to enhanced endothelial association. This study demonstrates the assembly and cellular association of a multiparticle delivery system that is biomolecularly targeted and has potential for applications in biological imaging.     

Diversity and community comparison indices: Assessing macroinvertebrate recovery following a gasoline spill

Diversity and community comparison indices were evaluated to determine their utility in quantifying macroinvertebrate response to a catastrophic gasoline spill into Wolf Lodge Creek, Idaho, U.S.A. The Shannon and Brillouin diversity indices, and the following community comparison indices were analyzed: (1) Jaccard's coefficient of similarity; (2) Renkonen's percentage similarity; (3) Bray-Curtis index; (4) Morisita's similarity index; (5) simplified Morisita index; (6) Canberra metric index; and (7) average χ² index. The Bray-Curtis and average χ² community comparison indices were more effective in quantifying differences in macroinvertebrate composition between gas-impacted and reference areas of Wolf Lodge Creek following the spill. In addition, these indices tracked the progressive spatial recolonization of macroinvertebrates during the 16 month recovery period. All other indices tested failed to adequately quantify macroinvertebrate community response to the gasoline spill.     

ESR investigations on polyethylene-single wall carbon nanotube composites

Electron spin resonance investigations on single wall carbon nanotubes dispersed in polyethylene are reported. Three resonance lines were observed; a wide line assigned to magnetic iron clusters (catalyst residues), a broad and intense line originating from uncoupled electrons delocalized over the conducting domains of carbon nanotubes (in interaction with the electronic spins assigned to magnetic impurities), and a faint line superimposed on the broad one, assigned to paramagnetic impurities. The temperature dependence of resonance line parameters (resonance line position, width, and double integral) in the range 150–450 K has been analyzed. It was observed that the parameters of the broad and narrow lines are sensitive to the glass and melting relaxations occurring within the polymeric matrix.     

Influence of pre-soaking conditions on ultrasonic extraction of Spirulina platensis proteins and its recovery using aqueous biphasic system

Ultrasonic aqueous extraction of proteins from dry Spirulina platensis at acidic (ACSU), alkali (ALSU), and neutral (NSU) conditions and its recovery using aqueous biphasic system (ABS) was studied. S. platensis was soaked in the solvent for 12 h prior to extraction. Neutral condition showed a higher protein release of 18.6 mg/ml at optimum conditions (solid–liquid ratio 1:20, 80% ultrasound amplitude, 100% ultrasound duty cycle, and 4ºC). The Box–Behnken design (BBD) suggested optimum conditions for ABS (PEG 6000, pH 8, and 5% NaCl) and gave 84.1% recovery. Although microscopic observations indicated structural changes, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier-transform infrared spectroscopy (FTIR) analyses confirmed that the proteins are intact.     

Alignment of carbon nanotubes and reinforcing effects in nylon-6 polymer composite fibers

Alignment of pristine carbon nanotubes (P-CNTs) and fluorinated carbon nanotubes (F-CNTs) in nylon-6 polymer composite fibers (PCFs) has been achieved using a single-screw extrusion method. CNTs have been used as filler reinforcements to enhance the mechanical and thermal properties of nylon-6 composite fibers. The composites were fabricated by dry mixing nylon-6 polymer powder with the CNTs as the first step, then followed by the melt extrusion process of fiber materials in a single-screw extruder. The extruded fibers were stretched to their maxima and stabilized using a godet set-up. Finally, fibers were wound on a Wayne filament winder machine and tested for their tensile and thermal properties. The tests have shown a remarkable change in mechanical and thermal properties of nylon-6 polymer fibers with the addition of 0.5?wt% F-CNTs and 1.0?wt% of P-CNTs. To draw a comparison between the improvements achieved, the same process has been repeated with neat nylon-6 polymer. As a result, tensile strength has been increased by 230% for PCFs made with 0.5% F-CNTs and 1% P-CNTs as additives. These fibers have been further characterized by DSC, Raman spectroscopy and SEM which confirm the alignment of CNTs and interfacial bonding to nylon-6 polymer matrix.