The Oxidative Coupling of 2,6-Xylenol Catalyzed by Polymeric Complexes of Copper, 2. Physicochemical Study on Copper(II) Complexes of Partially Dimethylaminomethylated Polystyrene

The polymeric catalyst formed by complexation of copper(II) chloride and partially dimethylaminomethylated polystyrene was investigated to explain its behaviour in the oxidative coupling of 2,6-xylenol. Viscometric studies indicated that at low polymer concentrations coordination of tertiary amine groups to copper(II) causes an intramolecular crosslinking. UV measurements and preliminary results of ESR point to a dimeric structure of these complexes with two amine groups per copper. A mechanism for the action of this polymeric catalyst is suggested, based on these results and on those described in Part 1. It appeared that some "free" copper(II) is essential for the catalytic activity, without which the reoxidation of copper(I) cannot take place.

A twelve year follow-up study on osteoarthritis of the knee in the general population : an epidemiological study of classification criteria, risk factors and prognostic factors

Criteria to diagnose the disease or assess the outcome need to be considered in every epidemiological study . The criteria are needed to classify participants as those having the disease or outcome and those who have not. Classification criteria are not always uniformly accepted and commonly more than one combination of criteria is used. The use of different classification criteria can lead to different study results and makes the comparison of different studies more difficult. Moreover, if nondifferential misclassi:fication occurs, the strength of an association between a putative risk factor and a disease is reduced as well as the power to detect an association. This methodological issue is discussed in more detail in this thesis with the aim of highlighting the consequences of this misclassification. Qassification criteria of knee osteoarthritis used in epidemiological research have almost always been based on radiographs. The criteria described by Kellgren and Lawrence have been used most commonly and were recommended for epidemiological studies at two international conferences (1,2,3). However, it was realized that these criteria should be validated and related to physical signs and symptoms (2). In this thesis the results of a study on the relationship of findings from the medical history, physical examination and serum analysis with radiographic osteoarthritis are presented. The aim of this study was to assess whether it was necessary to take a radiograph to diagnose radiographic osteoarthritis or whether it could be predicted reliably from the medical history, physical examination and serum analysis

The impact of contact effort on mode-specific selection and measurement bias

In 2011, a large-scale mixed-mode experiment was linked to the Crime Victimisation Survey (CVS). This experiment consisted of a randomized allocation of sample persons to the four contemporary survey modes Web, mail, telephone and face-to-face, and a follow-up using only interviewer modes. The aim of the experiment was to disentangle mode-specific selection- and measurement bias. In a previous paper (Schouten et al 2013), mode-specific selection and measurement biases were reported for a large number of key variables from the CVS and the Labour Force Survey. This paper is a follow-up to that study and investigates the size of the selection and measurement biases as a function of contact effort, where contact effort refers to the number of telephone calls, the number of face-to-face visits and the number of reminders in Web and mail. In the analyses, face-to-face response based on a maximum of six visits, the default face-to-face strategy at Statistics Netherlands, is used as the benchmark. The analyses show that contact effort has little impact on the size of measurement bias and a modest impact on the size of selection bias. From the results, it is therefore concluded that contact effort is not a strong common cause of nonresponse and measurement error

Role of fixed-combination brinzolamide 1%/timolol 0.5% in the treatment of elevated intraocular pressure in open-angle glaucoma and ocular hypertension

Brinzolamide 1%/timolol 0.5% is a new fixed-combination for the treatment of open-angle glaucoma or ocular hypertension. Brinzolamide/timolol has a favorable safety profile, with an incidence of ocular burning and stinging <5%. Published data show that brinzolamide 1%/timolol 0.5% and dorzolamide 2%/timolol 0.5% have similar efficacies for lowering intraocular pressure (IOP). There is some evidence that brinzolamide/timolol may be more comfortable. Although patients receiving brinzolamide/timolol may experience more blurred vision on instillation, some data show a preference for brinzolamide/timolol over dorzolamide/timolol. Although available data to assess the role of brinzolamide/timolol in daily clinical practice are still limited, these first results suggest the agent to be a reasonable alternative for patients who do not reach target IOP with monotherapy

Rapid and quantitative detection of homologous and non-homologous recombination events using three oligonucleotide MLPA

Embryonic stem (ES) cell technology allows modification of the mouse germline from large deletions and insertions to single nucleotide substitutions by homologous recombination. Identification of these rare events demands an accurate and fast detection method. Current methods for detection rely on Southern blotting and/or conventional PCR. Both the techniques have major drawbacks, Southern blotting is time-consuming and PCR can generate false positives. As an alternative, we here demonstrate a novel approach of Multiplex Ligation-dependent Probe Amplification (MLPA) as a quick, quantitative and reliable method for the detection of homologous, non-homologous and incomplete recombination events in ES cell clones. We have adapted MLPA to detect homologous recombinants in ES cell clones targeted with two different constructs: one introduces a single nucleotide change in the PCNA gene and the other allows for a conditional inactivation of the wild-type PCNA allele. By using MLPA probes consisting of three oligonucleotides we were able to simultaneously detect and quantify both wild-type and mutant alleles

Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents (Schouten et al. 2007), layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) which is the main contaminant in rinsing water. The main research question was to identify the effect of process parameters of the LDH synthesis on the stability of the LDH structure and the adsorption capacity of LAS. LDH was synthesized with the co-precipitation method of Reichle (1986); a solution of M2+(NO3)2 and M3+(NO3)3 and a second solution of NaOH and Na2CO3 were pumped in a beaker and mixed. The precipitate that was formed was allowed to age and was subsequently washed, dried and calcined. The process parameters that were investigated are the concentration of the initial solutions, M2+/M3+ ratio and type of cations. The crystallinity can be improved by decreasing the concentration of the initial solutions; this also decreases the leaching of M3+ from the brucite-like structure into the water. The highest adsorption capacity is obtained for Mg2+/Al3+ with a ratio 1 and 2 because of the higher charge density compared to ratio 3. Storing the LDH samples in water resulted in a reduction of adsorption capacity and a decrease in surface area and pore volume. Therefore, LDH is not applicable in a small device for long term use in aqueous surroundings. The adsorption capacity can be maintained during storage in a dry N2 atmosphere

Rapid and robust association mapping of expression quantitative trait loci

We applied a simple and efficient two-step method to analyze a family-based association study of gene expression quantitative trait loci (eQTL) in a mixed model framework. This two-step method produces very similar results to the full mixed model method, with our method being significantly faster than the full model. Using the Genetic Analysis Workshop 15 (GAW15) Problem 1 data, we demonstrated the value of data filtering for reducing the number of tests and controlling the number of false positives. Specifically, we showed that removing non-expressed genes by filtering on expression variability effectively reduced the number of tests by nearly 50%. Furthermore, we demonstrated that filtering on genotype counts substantially reduced spurious detection. Finally, we restricted our analysis to the markers and transcripts that were closely located. We found five times more signals in close proximity (cis-) to transcripts than in our genome-wide analysis. Our results suggest that careful pre-filtering and partitioning of data are crucial for controlling false positives and allowing detection of genuine effects in genetic analysis of gene expression