Index computations in Rabinowitz Floer homology

In this note we study two index questions. In the first we establish the relationship between the Morse indices of the free time action functional and the fixed time action functional. The second is related to Rabinowitz Floer homology. Our index computations are based on a correction term which is defined as follows: around a nondegenerate Hamiltonian orbit lying in a fixed energy level a well-known theorem says that one can find a whole cylinder of orbits parametrized by the energy. The correction term is determined by whether the periods of the orbits are increasing or decreasing as one moves up the orbit cylinder. We also provide an example to show that, even above the Ma?é critical value, the periods may be increasing thus producing a jump in the Morse index of the free time action functional in relation to the Morse index of the fixed time action functional.     

Pesticide analysis in ground water. Statistical evaluation of certification data of a multicomponent reference material

21 laboratories participated in the certification of a multicomponent ampouled reference material containing 24 pesticides. This paper describes the statistical analysis of the unbalanced data set returned by the participants in the certification. The simplest method of certification is achieved when laboratories report all the required data. In practice, however, with complex analytical methods such as multicomponent analyses of organic compounds, laboratories are not able to report all the required data. The response for each determinand in the material has been modelled in a three-factor nested model. For computational comfort the model has been rephrased into a general linear model. The statistical problems with unbalanced data are discussed in relation to ISO 5725 and ISO Guide 35. Tests for homogeneity are exact and uninfluenced by the unbalance in data. Unbalanced data cause dependencies between mean squares above the second lowest level of the model, thus exact hypothesis testing is not possible at higher levels. Approximate tests for variation between rounds and laboratories has been constructed by means of Satterthwaite’s formula [1]. A graphical plot of deviances from certified values has been applied to illustrate laboratory performance. Received: 25 May 1997 / Revised: 6 December 1997 / Accepted: 15 January 1998     

Examination of nonendocytotic bulk transport of nanoparticles across phospholipid membranes

Nonendocytotic transport is believed to play a role in the transmigration of particles less than 100 nm within biological systems. Determining the fundamental mechanism of this transport across cell membranes is essential if nanotechnology is to be utilized in general medical practice and may lead to methods of treating the deleterious internalization of ambient, possibly pollutant, nanoparticles. In order to gain a broader understanding of nonendocytotic transmembrane transport, it becomes essential to devise a method which allows the isolation of fundamental modes of transport such as passive Brownian diffusion through a membrane, as opposed to effusion-like transport of particles through transmembrane channels. The passive Brownian diffusion contribution was investigated using gold nanoparticles and mimetic biomembranes. Specifically, gold nanoparticle dispersions consisting of 7, 10, and 15 nm diameter particles were captured in giant unilamelar vesicles composed of phosphatidylcholine, phosphatidic acid, and cholesterol. Nonendocytotic transmembrane transport was modeled as the time derivative of the appearance of nanoparticles in the phosphate buffer outside the vesicles at 37 degrees C. The results show the transport rate to be zero; hence, a simple diffusive process of transmembrane transport is not supported.     

Molecular relaxations in ester‐terminated,amide‐based dendrimers

This study utilized Matrix Assisted Laser Desorption/Ionization Time‐of‐Flight Mass Spectrometry, Thermogravimetric Analysis, Differential Scanning Calorimetry, X‐Ray Diffraction, and Dielectric Analysis to assess the viscoelastic and structural properties of three generations of tert‐butyl and methyl ester, amide‐based dendrimers. The effect of generation number and functionality on glass‐transition temperatures and corresponding apparent activation energies, obtained via adherence to WLF behavior, were determined. Both were found to increase with increasing generation number and bulkiness of terminal functionalities. WLF constants, C₁ and C₂, allowed the determination of free volume, and thermal expansion coefficients, respectively. Secondary transitions, conforming to Arrhenius behavior, were also characterized and increased in temperature with generation number. The apparent activation energy was greater when the matrix was crystalline. Dielectric relaxation responses were analyzed to yield dielectric strengths of the molecular relaxations which increased with generation number and were comparable for both tert‐butyl and methyl esters in the glass‐transition region. Electrical properties of the dendrimers were dominated by ionic conductivity in the high temperature region. In order to unmask the glass transition, the data were treated in terms of the electric modulus. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2025–2038, 1999     

Quality management in wastewater treatment plants

A quality management system has been designed for process analyses in wastewater plants. The quality management concept consists of a quality manual, quality control charts used together with certified reference materials, and proficiency testing. Certified reference materials have been used to eliminate basic analytical errors. Proficiency testing has been conducted by VKI, the Reference Laboratory for Environmental Chemistry, subcontracted by the Danish Environmental Protection Agency. In the first proficiency test the analytical quality was comparable in general to the quality of routine environmental laboratories. One of the simplified analytical systems resulted, however, in a low recovery of nitrate in wastewater. The COD results reported in the proficiency test were slightly higher than the theoretical values.     

Pesticide analysis in ground water. Statistical evaluation of certification data of a multicomponent reference material

21 laboratories participated in the certification of a multicomponent ampouled reference material containing 24 pesticides. This paper describes the statistical analysis of the unbalanced data set returned by the participants in the certification. The simplest method of certification is achieved when laboratories report all the required data. In practice, however, with complex analytical methods such as multicomponent analyses of organic compounds, laboratories are not able to report all the required data. The response for each determinand in the material has been modelled in a three-factor nested model. For computational comfort the model has been rephrased into a general linear model. The statistical problems with unbalanced data are discussed in relation to ISO 5725 and ISO Guide 35. Tests for homogeneity are exact and uninfluenced by the unbalance in data. Unbalanced data cause dependencies between mean squares above the second lowest level of the model, thus exact hypothesis testing is not possible at higher levels. Approximate tests for variation between rounds and laboratories has been constructed by means of Satterthwaite’s formula [1]. A graphical plot of deviances from certified values has been applied to illustrate laboratory performance.     

Reference materials for monitoring nutrients in sea water environment

VKI, the Danish national reference laboratory for environmental chemistry, has prepared a range of reference materials for quality control of nutrient analyses in environmental samples. The relevant concentration levels and potential matrix interference effects vary with the sample type. In sea water, nutrient concentrations are in the g/L range and salt concentrations can cause matrix interferences. Two certified reference materials for nutrient analyses were prepared representing the salinities in the Kattegat (20–25 parts per thousand) and the Baltic sea (below 10 parts per thousand). The preparation and certification were an integrated part of a larger project conducted by VKI on the optimisation of nutrient analyses in sea water. Part of the project has been participation in a European interlaboratory trial exercise QUASIMEME [1], which has enabled the Danish reference material data to be traced back to other European data. Denmark has now a certified reference material that will help to ensure the quality of marine analyses that are part of the ongoing national water monitoring plan.     

The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

The co-pyrolysis of brominated high impact polystyrene (Br-HIPS) with polyolefins using a fixed bed reactor has been investigated, in particular, the effect that different types of brominated aryl compounds and antimony trioxide have on the pyrolysis products. The pyrolysis products were analysed using FT-IR, GC–FID, GC–MS, and GC–ECD. Liquid chromatography was used to separate the oils/waxes so that a more detailed analysis of the aliphatic, aromatic, and polar fractions could be carried out. It was found that interaction occurs between Br-HIPS and polyolefins during co-pyrolysis and that the presence of antimony trioxide influences the pyrolysis mass balance. Analysis of the Br-HIPS + polyolefin co-pyrolysis products showed that the presence of polyolefins led to an increase in the concentration of alkyl and vinyl mono-substituted benzene rings in the pyrolysis oil/wax resulting from Br-HIPS pyrolysis. The presence of Br-HIPS also had an impact on the oil/wax products of polyolefin pyrolysis, particularly on the polyethylene oil/wax composition which converted from being a mixture of 1-alkenes and n-alkanes to mostly n-alkanes. Antimony trioxide had very little impact on the polyolefin wax/oil composition but it did suppress the formation of styrene and alpha-methyl styrene and increase the formation of ethylbenzene and cumene during the pyrolysis of the Br-HIPS.