5 research outputs found
Op grond van beleid: Locaties voor sociale woningbouw, grondbeleid en ruimtelijke spreiding van welstand in en rond
No full textArchitectur
Ecological and physiological studies on freshwater autotrophic picoplankton
No full textA series of studies were conducted to ascertain the importance of autotrophic picoplankton (0.2 - 2.0 fm in the longest dimension) in freshwaters. These included surveys of populations in lakes and rivers, and experiments on strains which had been isolated in clonal, axenic culture. Methods were developed to preserve, count and identify autotrophic picoplankton. Epifluorescence microscopy was used routinely throughout the study and it was shown that cells could be preserved in buffered formalin or glutaraldehyde for at least 12 months without a loss in cell count. Autotrophic picoplankton fluoresced red or orange depending on the photosynthetic pigments present, and a method based on fluorescence characteristics was developed to distinguish cyanobacterial from eukaryotic cells. Eukaryotes fluoresced most intensely under blue excitation light and were barely visible under green excitation light and cyanobacterial cells had the reverse response. In addition, fluorescence from eukaryotic cells faded faster than the fluorescence from cyanobacterial cells. Samples from standing waters from around the world were collected from 5 continents in a survey to discover how widespread autotrophic picoplankton are in the world; densities ranged from 1.02 x 10(^6) from a pool in Saudi Arabia to 1.20 x 10(^6) in Ennerdale Water in the UK. A survey of 30 lakes in northern England and Scotland revealed autotrophic picoplankton in every sample. Cell densities ranged from a minimum of 1.02 x 10(^2) in Esthwaite Water to a maximum of 4.26 x 10(^5) in Ennerdale Water. In two mountain streams the only autotrophic picoplankton found were aberrant. Studies on the seasonality of autotrophic picoplankton from 10 UK lakes showed that population densities differed by at least two orders of magnitude in a year. In every lake densities reached a maximum at mid- to late summer and highest densities were found in nutrient-poor waters. There was a marked difference in the relative abundance of orange and red fluorescing cells in all lakes. A number of standard methods were used to isolate and purify strains of autotrophic picoplankton, including a novel method using a laser flow cytometer to purify bacterized unialgal cultures. 14 strains were studied (9 obtained the author) and they demonstrated different growth rates when grown with different nitrogen substrates and when grown under different photon flux density. Twelve strains showed cell-bound phosphomonoesterase activity at pH 10.3 and nine strains showed cell bound phosphodiesterase activity at pH 10.3. No strain showed evidence of nitrogen fixation, chemoheterotrophic growth, desiccation tolerance, motility nor chromatic adaptation
A study of the wear process related to twin-screw extruders
No full textExtruders are used in a wide range of process industries and high reliability is essential if cost
effective manufacturing is to be maintained. A critical part of twin-screw extruders is the barrel
that must withstand many different wear and corrosion environments depending on the end user.
For many applications the extruder barrel is a critical component and it is essential that it performs
in a predictable manner, providing the necessary design life-time.
This project has addressed these aims by considering the wear/corrosion behaviour of current and
potential extruder barrel materials from which a life prediction model has been developed.
A wide range of engineering materials has been evaluated in the laboratory for abrasive wear
resistance using a dry sand abrasive wear test according to ASTM G 65-93. An appraisal of the
tests and the applicability of the results to the in-service conditions of an extruder has lead to
further testing for abrasion and abrasion-corrosion resistance of four materials, namely Mild Steel,
440C, N18 and N18+5%TiC+5%TiN.
Plastic deformation was the main feature of the damaged surfaces in the form of ploughing which
has been modelled in terms of a low-cycle fatigue process. The relative hardness between material
and abrasive was found to be an important parameter in controlling the rate of material removal.
It has also been shown that the synergistic effect of abrasion-corrosion results in an accelerated
material removal rate.
The information from these tests has been used to develop a model of the wear of extruder barrels
by abrasive particles. It is shown that there is a correlation between the particle size, wear debris
size and wear groove size distributions. From a knowledge of the particle flux, the particle size
distribution and the loading conditions, metal recession is predicted based on a low-cycle fatigue
process. The wear rates for a wide range of Fe- and Ni-based materials are predicted to better
than a factor of two.
When corrosion is also present, the mechanism of metal recession depends on whether passive
surface films are formed. For the Fe-based materials which exhibit direct dissolution of material,
the wear/corrosion rate can be estimated by combining the metal loss rate under pure wear and
pure corrosion conditions only. For the Ni-base alloys, thin passive films form in all the aqueous
environments studied and corrosion rates are extremely low. However, during abrasive wear the
passive films are removed and the overall metal recession rate is a combination of metal loss due
to abrasive wear of the substrate and the continual formation and removal of surface passive films
High levels of polypharmacy in rheumatoid arthritis—a challenge not covered by current management recommendations : data from a large real-life study
No full textRheumatoid arthritis (RA) is associated with high frequency of comorbidities and increased risk of polypharmacy. Although there is a great potential for complications, there is a gap in literature on polypharmacy in patients with rheumatic arthritis. To evaluate the prevalence and factors associated with polypharmacy in a population in a real-life setting. Methods: A cross-sectional multicenter study was conducted in Brazil. Patients underwent clinical evaluation and medical records analysis. Polypharmacy was considered as a dependent variable. To test independent variables, we used Poisson regression. We evaluated 792 patients (89% female, median age 56.6 years). Median duration of disease was 12.7 years, 78.73% had a positive rheumatoid factor. The median of disease activity score-28 was 3.5 (disease with mild activity), median of the clinical disease activity index score was 9, and median of health assessment questionnaire-disability index was 0.875; 47% used corticosteroids, 9.1% used nonsteroidal anti-inflammatory drugs, 90.9% used synthetic disease-modifying antirheumatic drugs, 35.7% used biologic disease-modifying antirheumatic drugs (DMARDs). In total, 537 (67.9%) patients used 5 or more drugs. Polypharmacy showed a relationship with a number of comorbidities and use of specific drugs (corticosteroids, methotrexate, and biological DMARDs). We found a high prevalence of polypharmacy (67.9%) in RA. Solutions to management this problem should be stimulatedThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Brazilian Society of Rheumatology (BSR). For this project, BSR received specific grant support from the following companies: Bristol-Myers Squibb Farmacêutica Ltda; Eli Lilly do Brasil Ltda; Janssen-Cilag Farmacêuticos Ltda; Laboratórios Pfizer Ltda; Produtos Roche Químicos e Farmacêuticos S.A.; and UCB Biopharma Ltda. The funding body or the companies had no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscrip
