Search results for "relation"

STUDENT TEACHERS’ PROBLEMS IN TEACHING ‘ELECTROLYSIS’ WITH A KEY DEMONSTRATION

2002

This study is concerned with student teachers’ conceptions about teaching the topic of electrolysis and difficulties they encounter. The aim of the study was also to find out how the student teachers understand the meaning of a key demonstration that would show the main features of the phenomenon. During this study eight chemistry student teachers were invited to write a lesson plan on the topic of electrolysis for lower secondary level, grade 8 pupils (age 14 to 15). The written lesson plans and the semi-structured interviews were collected and analysed by using a set of analytical categories. Only two of the eight student teachers had a clear view that electrolysis is a process where an e…

Mapping the Teaching of History of Chemistry in Europe

2016

Recent developments in the field of history of chemistry have introduced new topics, challenges, and connections to a broad range of scientific, political, cultural, economic, and environmental issues. New audiences for the history of chemistry have emerged along with new topics, protagonists, spaces, and historical narratives. This paper summarizes the main results of a recent survey to map the current situation of the teaching of history of chemistry in Europe. We review how and where history of chemistry is taught in Europe, considering not only graduate students in science programs, but also other audiences such as science teachers, and the general public. This paper also provides updat…

Modeller i kjemiundervisning - et eksempel på hvordan de kan bidra til læring og feillæring

2021

We discuss the use of analogical models in science education using examples from online learning resources.  We have conducted a teaching program for a group of 7th grade pupils and a group of science teacher students, and the main theme of this program is the use of models in chemistry. Specifically, we study the effect of an analogical model that is designed to promote understanding of the properties of molecules, related to a paper chromatography experiment. Our research indicates that analogical models can be a useful tool to convey understanding of abstract concepts and non-visible phenomena, but they hold serious pitfalls that can lead to misunderstandings amongst students if not used…

Retinol encapsulated into amorphous Ca2+ polyphosphate nanospheres acts synergistically in MC3T3-E1 cells

2015

Both the quality and quantity of collagen, the major structural component of the skin, decrease in aging skin. We succeeded to encapsulate retinol into amorphous inorganic polyphosphate (polyP) nanoparticles together with calcium ions ("aCa-polyP-NP"), under formation of amorphous Ca-polyP/retinol nanospheres ("retinol/aCa-polyP-NS"). The globular nanospheres are not cytotoxic, show an almost uniform size of ≈ 45 nm and have a retinol content of around 25%. Both components of those nanospheres, retinol and the aCa-polyP-NP, if administered together, caused a strong increase in proliferation of mouse calvaria MC3T3 cells. The expressions of collagen types I, II and III genes, but not the exp…

Activity–Bioavailability balance in Oral Drug Development for a Selected Group of 6‐Fluoroquinolones

2002

Abstract A nomogram is proposed to select the best candidate in drug development studies with quinolones and is intended to substitute other possible models. The nomogram is referred to as an activity–bioavailability balance (ABB) because it includes the following two criteria: ABB= 1 / gm MIC ( drug candidate ) 1 /gm MIC ( ciprofloxacin ) · F calc \( drug candidate \) F calc ( ciproflaxacin ) . The in vitro activity of a group of 4′ N ‐alkyl‐ciprofloxacin derivatives was determined together with that of ciprofloxacin, initially against some reference strains and subsequently against 159 clinical isolates of eight selected species. The inverse of the geometric mean of the lowest concentrati…

Prediction of acute toxicity of organophosphorus pesticides using topological indices

2007

Topological indices were used in the prediction of the acute toxicity (intraperitoneal and oral LD(50)) of organophosphorus pesticides on rats. Models with six variables for the prediction of LD(50)-i.p. (r = 0.849, Q(2) = 0.613) and eight variables for LD(50)-oral (r = 0.906, Q(2) = 0.701) were selected. External group and cross-validation by use of leave-n-out tests were also performed in order to assess the stability and the prediction performance of the selected topological models.

<title>Time-resolved fluorescence study of interaction of the monoclonal anticoproporphyrin antibodies and (Pt-)coproporphyrin</title>

1995

Mechanisms of ligand binding by monoclonal anti-coproporphyrin antibodies are studied by steady-state and time-resolved fluorescence spectroscopy by use of a picosecond laser system. The antibodies quench the coproporphyrin (CP) fluorescence, but the CP fluorescence spectra show a strong shift of maxima at high concentrations of antibodies (Ab) or their Fab fragment. This can be explained by a special type of Ab or Fab dimerization. Fluorescence decays of CP are measured at different concentrations of Ab and different pH values. The following deconvolution procedure based on the non-linear least squares method reveals a two- exponential character of the fluorescence decay. Data obtained by …

Size Dependence of Tracer Diffusion in Supercooled Liquids

1996

We have determined by forced Rayleigh scattering the diffusion coefficients D of several photochromic tracers with van der Waals radii between 0.38 and 8 nm (the largest ones being photolabeled polystyrene micronetworks) in 10 glass-forming liquids at temperatures between the glass temperature Tg and ∼1.2Tg. The results were analyzed in terms of power law plots, D(T) ∝ T/η(T)ξ, where η is the solvent shear viscosity, and temperature shifts, D(T) ∝ T/η(T + ΔT). The shift ΔT was related with the width of the rotational correlation time distribution via the time−temperature superposition principle.

Emil Fischer — Unequalled Classicist, Master of Organic Chemistry Research, and Inspired Trailblazer of Biological Chemistry

2003

Synthesis, Crystal Structure and Magneto‐Structural Correlation of an Unusual Thiocyanato‐Bridged Nickel( II ) Compound, [Ni(μ‐NCS)(dpt)(NCS)] 2 [Ni(…

2003

Reaction of Ni(ClO4)2·6H2O with bis(3-aminopropyl)amine (dpt) and ammonium thiocyanate produces the novel thiocyanato-bridged nickel(II) compound [Ni(μ-NCS)(dpt)(NCS)]2[Ni(μ-NCS)(dpt)(NCS)]4, which has been structurally characterised. The structure determination reveals that there are two different molecules in the crystal lattice; one is dinuclear and other is tetranuclear. Low-temperature magnetic measurements show that there are ferro- as well as antiferromagnetic interactions. The ferromagnetic interaction arises from the dinuclear part and the doubly bridged part of the tetranuclear unit; the antiferromagnetic interaction occurs between singly bridged nickel centres in the tetranuclear…