Base-catalyzed condensation of citral and acetone at low temperature using modified hydrotalcite catalysts

A study on the catalytic properties of properly activated hydrotalcite (HT) with special attention to the nature and amount of active sites present in this solid base catalyst has been undertaken. Only a small fraction (5%) of the available basic sites in the rehydrated calcined HT is active in liquid-phase aldol condensations. These sites exhibit high catalytic activity and are most likely localized at the edges of the HT-platelets. Besides a high activity, these modified HTs also show a high selectivity. No further condensation products other than diacetone alcohol (DAA) in the acetone self-condensation could be observed. Initial results with the citralacetone condensation show that even at 273 K this reaction is catalyzed by modified HTs with a conversion of 65% and a selectivity of 90%, when the citral concentration is not too high ( 1 wt.%). At higher citral concentrations, no reaction is observed indicating a negative order in citral concentration. © 2000 Elsevier Science B.V. All rights reserved

Monitoring Oyster Point seagrasses : 1995 to 1999

In the present report, an assessment of changes in seagrass distribution and abundance since the baseline (November 1995) and previous monitoring surveys of December 1997 and November 1998 is included. We provide a quantification of changes between years and comment on the possible impacts of the dredging program

Electrical and catalytic properties of some oxides with the fluorite or pyrochlore structure: Part 2: Catalytic oxidation of carbon monoxide

The catalytic properties of mixed oxides with the fluorite or pyrochlore structure were investigated using CO oxidation. The presence of ions with a variable valence state, the size of the ions and especially the extent of pyrochlore ordering affect kinetic behaviour and activity of the investigated materials

Electrical and catalytic properties of some oxides with the fluorite or pyrochlore structure: Part 1: Synthesis, characterization and conductivity

In view of their possible use as electrocatalysts, several oxides with the fluorite or pyrochlore structure were investigated. Part I of this paper deals with the synthesis, characterization and electrical conductivity of these materials. All lanthanide titanates investigated (partly doped with Bi) show the pyrochlore structure and are poor conductors, except for the compounds containing Tb. For Nd-zirconates, partly substituted with Ce, the degree of order depends on the amount of Ce and temperature treatment. Ionic and in some cases mixed conductivity was observed. Part II reports about the catalytic activity for CO oxidation

Baseline survey of Hinchinbrook region seagrasses - October (spring) 1996

Current coastal zone management issues in the Hinchinbrook region include protection of fisheries habitats, dugong habitat areas and increases in aquaculture, agriculture and tourist operations. A regional coastal management plan which is being developed, also requires detailed information on seagrass resources for the coastal zone from Dunk Island in the north, to Cleveland Bay in the south. Decreases in estimates of dugong abundance in the southern half of the Great Barrier Reef region since the 1980's have also prompted the need for detailed baseline and monitoring surveys of seagrasses in this and other regions

Improving mental health of student and novice nurses to prevent dropout: A systematic review

Aims: To provide: (a) an overview of interventions aimed at improving mental health of student or novice nurses; and (b) an evaluation of their effectiveness on dropout-related outcomes. Design: Systematic review. Data sources: Research papers published between January 1971–February 2019 were identified from the following databases: Embase, Medline, PsycInfo, CINAHL, ERIC, the Cochrane Library, Web of Science, and Google Scholar. Review methods: We followed the procedures recommended by the Editorial Board of the Cochrane Collaboration Back Review Group. We included peer-reviewed articles with a quantitative research design, examining interventions aimed at improving mental health of student and novice nurses and their effect on dropout-related outcomes. The large variation in studies prohibited statistical pooling and a synthesis without meta-analysis of studies was performed. Results: We identified 21 studies with three areas of focus: managing stress or stressors (N = 4); facilitating the transition to nursin

Cell-based Approaches to Joint Surface Repair : A Research Perspective

The authors are grateful for support to their research from Arthritis Research UK (grants 19271, 19429, 19667, 20050). None of the authors received any funding related to the writing of this manuscript, and the funding bodies did not play any role in the writing of the manuscript or decision to submit the manuscript for publication.Peer reviewedPublisher PD

Critical behavior of the two-dimensional N-component Landau-Ginzburg Hamiltonian with cubic anisotropy

We study the two-dimensional N-component Landau-Ginzburg Hamiltonian with cubic anisotropy. We compute and analyze the fixed-dimension perturbative expansion of the renormalization-group functions to four loops. The relations of these models with N-color Ashkin-Teller models, discrete cubic models, planar model with fourth order anisotropy, and structural phase transition in adsorbed monolayers are discussed. Our results for N=2 (XY model with cubic anisotropy) are compatible with the existence of a line of fixed points joining the Ising and the O(2) fixed points. Along this line the exponent $\eta$ has the constant value 1/4, while the exponent $\nu$ runs in a continuous and monotonic way from 1 to $\infty$ (from Ising to O(2)). For N\geq 3 we find a cubic fixed point in the region $u, v \geq 0$, which is marginally stable or unstable according to the sign of the perturbation. For the physical relevant case of N=3 we find the exponents $\eta=0.17(8)$ and $\nu=1.3(3)$ at the cubic transition.Comment: 14 pages, 9 figure