Polymer-modified glass fibre reinforced gypsum

Glass fibre reinforced gypsum, modified by addition of specially selected and developed thermosetting polymers, is the basis of a new composite material, called PGRG. An investigation has been performed into its mechanical properties such as bending strength, tensile strength and long-term performance under constant load and fatigue load. The influence of moisture and temperature on mechanical properties has been determined. The equilibrium moisture content at various relative humidities, the moisture content under natural weathering conditions, the coefficient of linear expansion and the microstructure have been studied. Furthermore, the durability has been investigated under accelerated ageing conditions and outdoor exposure. The results have shown that the polymer-modified glass fibre reinforced gypsum has good mechanical properties under tension and, unlike unmodified gypsum, is resistant to the Western European climate. A variety of new outdoor applications for gypsum are likely to be possible now: The material has already been used successfully for outdoor applications in the UK, the Middle East and The Netherlands.

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Resume Le platre renforcé de fibres de verre, modifié par l'addition de polymère thermodurcissable spécialement sélectionné et fabriqué, forme la base d'un nouveau matériau composite appelé PGRG, dont on a examiné certaines propriétés mécaniques: résistance à la flexion, à la traction et performance à long terme sous charge constante et charge de fatigue. On a déterminé l'influence de l'humidité et de la température sur les propriétés mécaniques. On a également étudié l'équilibre de la teneur en eau à différentes humidités relatives, la teneur en eau en exposition naturelle, le coefficient d'expansion linéaire et la microstructure. On a aussi examiné la durabilité dans des conditions de vieillissement accéléré et l'exposition à l'atmosphère. Les résultats ont montré que les propriétés mécaniques du composite sont bonnes et que, à la différence du platre non traité, il peut résister au climat d'Europe Occidentale. Ceci permet d'envisager maintenant pour le platre diverses applications en ouvrages extérieurs. Le matériau a déjà été utilisé avec succès pour ce type d'applications en Grande-Bretagne, aux Pays-Bas et au Moyen-Orient.

     

Plant-wide (BSM2) evaluation of reject water treatment with a SHARON-Anammox process.

In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 (BSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where reject water is recycled to the primary clarifier, i.e. the BSM2 plant, shows that the ammonium load of the influent to the primary clarifier is 28% higher in the case of reject water recycling. This results in violation of the effluent total nitrogen limit. In order to relieve the main wastewater treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios is performed using an Operating Cost Index (OCI).     

Percutaneous bile duct drainage; experiences with a new type of endoprosthesis]

Self expandable stents were placed percutaneously in 105 patients with malignant biliary obstruction. Stent diameter was 1 cm; length, 3.5-10.5 cm. Of the 60 patients with common bile duct obstruction, 50 died 0.2-12 months (median 3 months) after stent insertion. Two patients developed recurrent jaundice and cholangitis after 6 and 12 months, respectively. One patient underwent reintervention. Ten patients, one after a successful reintervention, were alive without jaundice 1-8 months (median 5 months) after stent placement. Of the 45 patients with hilar lesions, 26 died 0.7-18 months (median 5 months) after stent placement, five of them with signs of cholangitis. Nineteen are alive 1-21 months (median 7 months) afterwards. Reinterventions were carried out in 13 patients (29%). The most common cause of stent malfunction was tumour overgrowth. Stent-related complications were seen in three patients.     

Pseudomutagenesis. The persistent increase in the level of cellular variability induced by radiation and some other agents

Electron microscopic investigation of capillary endothelium cells in myocardium of irradiated rats revealed an unusual effect of persistent increase of probability of cell damage, similar in many relations to that described earlier for various unicellular species. New effect, unlike those traditionally studied, is characterised by non-stochastic nature, large number of the involved cells, reveals itself even after faint influences, and can be induced as well by agents other than radiation. The question is put on the probable commonness between these changes and the pseudomutagenesis which has the similar phenomenology.     

Adenoma characteristics at first colonoscopy as predictors of adenoma recurrence and characteristics at follow-up. The Polyp Prevention Study Group

In Bacillus transformation, sexual isolation is known to be an exponential function of the sequence divergence between donor and recipient. Here, we have investigated the mechanism under which sequence divergence results in sexual isolation. We tested the effect of mismatch repair by comparing a wild-type strain and an isogenic mismatch-repair mutant for the relationship between sexual isolation and sequence divergence. Mismatch repair was shown to contribute to sexual isolation but was responsible for only a small fraction of the sexual isolation observed. Another possible mechanism of sexual isolation is that more divergent recipient and donor DNA strands have greater difficulty forming a heteroduplex because a region of perfect identity between donor and recipient is required for initiation of the heteroduplex. A mathematical model showed that this heteroduplex-resistance mechanism yields an exponential relationship between sexual isolation and sequence divergence. Moreover, this model yields an estimate of the size of the region of perfect identity that is comparable to independent estimates for Escherichia coli. For these reasons, and because all other mechanisms of sexual isolation may be ruled out, we conclude that resistance to heteroduplex formation is predominantly responsible for the exponential relationship between sexual isolation and sequence divergence in Bacillus transformation.     

Lens transmission by fluorophotometry after brachytherapy and thermotherapy of choroidal melanoma

We studied the effect of transpupillary thermotherapy (TTT) by a diode laser at 810 nm combined with episcleral ruthenium-106 plaque treatment (106Ru) on lens transparency in patients with choroidal melanoma. Lens transmission of blue-green light was measured by fluorophotometry in 17 patients treated with 106Ru treatment and TTT (measured 0.36 years after treatment), 12 patients treated with 106Ru alone (measured 19 years after treatment) and 25 age-matched healthy controls. Differences in lens transmission were not significant between treated and untreated fellow eyes (p > 0.15) nor between patient and control eyes (p > 0.25). TTT of choroidal melanoma combined with 106Ru plaque irradiation did not have a significant effect on the lens transparency up to 6 years after treatment.     

High-speed gel-spinning of ultra-high molecular weight polyethylene

Summary This communication is concerned with the gel-spinning of ultrahigh molecular weight polyethylene (UHMWPE) at speeds up to 1500 m/min. It was found that 5 wt% solutions of UHMWPE in paraffin oil could be extruded through a conical die at a rate of 100 m/min. without the appearance of filament irregularities due to elastic solution fracture. These elastic turbulences occur at extrusion speeds of about 5 m/min. Without the addition of 1 wt% of Aluminium-stearate the spinline could be stretched at most to 60 m/min at 170°C but at 210°C it did not break at a speed of 1500 m/min.These high-speed gel-spinning experiments at temperatures around 200°C yielded polyethylene fibers with a tensile strength of 3.5 GPa. It was observed that drying of the as-spun fiber containing n-hexane at constant length led to excessive crazing.