Louisiana State University

About: Louisiana State University is a education organization based out in Baton Rouge, Louisiana, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 40206 authors who have published 76587 publications receiving 2566076 citations. The organization is also known as: LSU & Louisiana State University and Agricultural and Mechanical College.

Spray Coatable Electrochromic Dioxythiophene Polymers with High Coloration Efficiencies

Abstract: Four new disubstituted propylenedioxythiophene polymers have been synthesized by Grignard metathesis on the 1−5 g scale. All polymers were found to be soluble in chloroform, methylene chloride, toluene, and tetrahydrofuran and were fully structurally characterized having GPC determined number-average molecular weights ranging from 33000 to 47000 g mol-1. Dilute polymer solutions in toluene exhibited strong red fluorescence with moderate quantum efficiencies from 0.38 to 0.50. Homogeneous thin films were formed by electropolymerization and spray casting polymer solutions onto ITO coated glass slides at thicknesses of ca. 150 nm. The films were electroactive, switching from a dark blue-purple to a transmissive sky blue upon p-doping, often with subsecond switching times, and high electrochromic contrast luminance changes (% ΔY) of 40−70%. These studies revealed that the branched derivatives, [poly(3,3-bis(2-ethylhexyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)] and [poly(6,8-dibromo-3,3-bis(2-ethylhexylox...

Ant-aphid mutualisms: the impact of honeydew production and honeydew sugar composition on ant preferences.

Abstract: The honeydew composition and production of four aphid species feeding on Tanacetum vulgare, and mutualistic relationships with the ant Lasius niger were studied. In honeydew of Metopeurum fuscoviride and Brachycaudus cardui, xylose, glucose, fructose, sucrose, maltose, melezitose, and raffinose were detected. The proportion of trisaccharides (melezitose, raffinose) ranged between 20% and 35%. No trisaccharides were found in honeydew of Aphis fabae, and honeydew of Macrosiphoniella tanacetaria consisted of only xylose, glucose and sucrose. M. fuscoviride produced by far the largest amounts of honeydew per time unit (880 μg/aphid per hour), followed by B. cardui (223 μg/aphid per hour), A. fabae (133 μg/aphid per hour) and M. tanacetaria (46 μg/aphid per hour). The qualitative and quantitative honeydew production of the aphid species corresponded well with the observed attendance by L. niger. L. niger workers preferred trisaccharides over disaccharides and monosaccharides when these sugars were offered in choice tests. The results are consistent with the ants' preference for M. fuscoviride, which produced the largest amount of honeydew including a considerable proportion of the trisaccharides melezitose and raffinose. The preference of L. niger for B. cardui over A. fabae, both producing similar amounts of honeydew, may be explained by the presence of trisaccharides and the higher total sugar concentration in B. cardui honeydew. M. tanacetaria, which produced only low quantities of honeydew with no trisaccharides was not attended at all by L. niger.

Hurricane‐forced upwelling and chlorophyll a enhancement within cold‐core cyclones in the Gulf of Mexico

Abstract: [1] Clear skies, subsequent to Hurricane Ivan's passage across the Gulf of Mexico in September 2004, provided a unique opportunity to investigate upper ocean responses to a major hurricane Oceanic cyclonic circulation was rapidly intensified by the hurricane's wind field (59-62 m s -1 ), maximizing upwelling and surface cooling (3-7°C) in two large areas along Ivan's track Upward isothermal displacements of 50-65 m, computed from wind stress and sea surface height changes, caused rapid ventilation of thermoclines and nutriclines, leading to phytoplankton blooms with peak concentrations 3-4 days later Wind speed changes along Ivan's track demonstrated that the cool waters (20-26°C) provided immediate negative feedback to the hurricane's intensity Although our study focused on a relatively small ocean area, it revealed that mesoscale cyclones, in addition to warm anticyclones, may play an important role in producing along-track hurricane intensity changes

In vitro evaluation of shear bond strengths of resin to densely-sintered high-purity zirconium-oxide ceramic after long-term storage and thermal cycling

Abstract: Statement of problem The few available studies on the resin bond to zirconium-oxide ceramic recommend airborne-particle abrasion and modified resin luting agents containing adhesive monomers for superior and long-term durable bond strengths. It is unknown whether this regimen can also be successfully applied to the intaglio surface of a commercial zirconia-based all-ceramic system. Purpose The purpose of this study was to evaluate and compare bond strengths of different bonding/silane coupling agents and resin luting agents to zirconia ceramic before and after artificial aging. Material and methods Composite cylinders (2.9 mm × 3.0 mm) were bonded to airborne-particle–abraded intaglio surfaces of Procera AllZirkon specimens (n=80) with either Panavia F (PAN) or Rely X ARC (REL) resin luting agents after pretreatment with Clearfil SE Bond/ Porcelain Bond Activator (Group SE). In another group, Rely X ARC was used with its bonding/silane coupling agent (Single Bond/Ceramic Primer, Group SB). PAN without any bonding/silane agent (Group NO) was the control. Subgroups of 10 specimens were stored in distilled water for either 3 or 180 days before shear bond strength was tested. One hundred eighty–day–old specimens were repeatedly thermal cycled for 12,000 cycles between 5 and 60°C with a 15-second dwell time. Data were analyzed with 1- and 2-way analysis of variance and the Tukey multiple comparisons test (α=.05). Failure modes were examined under original magnification ×25. Results After 3 days, SE-REL (25.15 ± 3.48 MPa) and SE-PAN (20.14 ± 2.59 MPa) groups had significantly superior mean shear bond strengths ( P =.0007) compared with either NO-PAN (17.36 ± 3.05 MPa) or SB-REL (16.90 ± 7.22 MPa). SE-PAN, NO-PAN, and SB-REL groups were not significantly different. Artificial aging significantly reduced bond strengths. After 180-day storage, SE-PAN (16.85 ± 3.72 MPa), and SE-REL (15.45 ± 3.79 MPa) groups demonstrated significantly higher shear bond strengths than NO-PAN (9.45 ± 5.06 MPa) or SB-REL (1.08 ± 1.85 MPa) groups. The modes of failure varied among 3-day groups but were 100% adhesive at the ceramic surfaces after artificial aging. Conclusion Artificial aging significantly reduced bond strength. A bonding/silane coupling agent containing an adhesive phosphate monomer can achieve superior long-term shear bond strength to airborne-particle– abraded Procera AllZirkon restorations with either one of the 2 resin luting agents tested.