An alternating low band-gap polyfluorene for optoelectronic devices

An alternating polyfluorene (APFO) with low band-gap segments named APFO-Green1 has been designed and synthesized for use in optoelectronic devices. The low band-gap segment consists of an electron acceptor (A), fenced by electron donors (D). This D-A-D configuration leads to a partial charge transfer in the polymer backbone, and thereby a low band-gap (1.3 eV). Results obtained from characterization of APFO-Green1 include light absorption and emission at extended wavelengths as well as high hole mobility. Furthermore, blends of the polymer with different fullerene derivatives exhibit unusually high photovoltaic performance at long wavelengths, making this type of conjugated polymers promising for plastic solar cell applications.     

A viscoplastic material model and its application to cyclic loading

Summary A kinematic hardening model is generalized by introducing plastic and viscous residual back stresses , that govern the translation of the yield surface. The evolution equations for and are proposed and the material functions are identified for a construction steel by carrying out tension-compression tests at different strain rates. The cyclic tests with changing strain amplitudes and frequencies are next carried out and model predictions are compared with experimental results.

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Ein viskoplastisches Stoffmodell und seine Anwendungen bei zyklischer Belastung

Zusammenfassung Ein Modell mit kinetmatischer Verfestigung wird durch die Einführung plastischer und viskoser bleibender Hintergrundspannungen , verallgemeinert, die die Bewegungen der Fließfläche steuern. Die Wachstumsgleichungen für und werden aufgestellt und die Materialfunktionen für einen Baustahl aus Zug-Druckversuchen mit verschiedener Dehnungsrate bestimmt. Die zyklischen Versuche mit sich ändernden Dehnungsamplituden und Fequenzen werden als nächstes durchgeführt und die Modellaussagen mit den experimentellen Ergebnissen verglichen.

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With 14 Figures     

Epoxidation of soybean oil by the methyltrioxorhenium-CH2Cl2/H2O2 catalytic biphasic system

We studied the methyltrioxorhenium (MTO)-CH₂Cl₂/H₂O₂ biphasic system for epoxidizing soybean oil. The reactions were optimized (reactant ratio, time, and temperature), which resulted in a better performance (higher conversion and selectivity) than those described in the literature. Total doublebond conversion and 95% selectivity were obtained in 2 h at room temperature. Furthermore, it was possible to reach desired epoxidation degrees by changing the oxidant and MTO amounts. The rhenium-epoxidized soybean oil remained stable in the absence of stabilizers for up to 30 d when stored at mild conditions.     

Natural estolides produced by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. 42A2 grown on oleic acid: Production and characterization

Estolides are a group of FA polyesters resulting from ester bond formation between a hydroxyl or olefinic group of one FA and the terminal carboxyl group of a second FA. These products are commonly found in trace amounts, forming tetraglycerides in several oil seed plants, and have been produced by acid clay and enzymatic catalysis in vitro. In this study, natural estolides produced by a bacterial culture are presented for the first time. Pseudomonas sp. 42A2 produced (E)-10-hydroxy-8-octadecenoic acid and (E)-7,10-dihydroxy-8-octadecenoic acid when grown on oleic acid. It is suggested that these FA were polymerized in culture by a lipase produced by the bacterial strain, resulting in a mixture of estolides. These compounds amounted to 3.8 g/L after 72 h of incubation. LC-MS analysis indicated that the types of estolides formed were dimers (m/z 560–610), trimers (m/z 845–906), tetramers (m/z 1122–1202), pentamers (m/z 1328–1424), and hexamers (m/z 1554–1788), with a relative abundance of 27.5, 19.4, 15, 9.7, and 11%, respectively. This is the first report in which hexamers were detected in a bacterial culture.     

Kidney hypoplasia and hypertension

The basis of the examination is a clinical material of 14 years (from 1960 to 1973) of the urological clinic of the Medical University "Semmelweis", consisting of 160 patients with renal hypoplasia. In 116 of these cases a nephrectomy was performed. The average postoperative observation time was 7.8 years. By removal of the hypoplastic kidney the hypertension could be successfully influenced in 72% of the cases and in 16% moderately; in 12% of the patients the high blood pressure remained unchanged also after the intervention. On account of the recognition resulting from the examinations that by the hypoplastic kidney alone no increase of the blood pressure is caused, but the developmental anomaly forms a basis for the development of the hypertension, is emphasized that the early removal of this abnormally developed kidney is by all means indicated.     

Systemic lupus erythematosus in children: the complex problems of diagnosis and treatment encountered in 101 such patients at the Mayo Clinic

Between 1945 and 1970, 101 children (86 girls and 15 boys) with systemic lupus erythematosus were evaluated at the Mayo Clinic. Only 9 children were less than 9 years old at the time of diagnosis. The most frequent presenting complaint was arthralgia; fever, fatigue, and a "butterfly" malar rash also were common. Renal involvement, found in more than 76 per cent of patients, was a prognostically poor sign. The overall survival of children with renal involvement is improved by the use of adequate steroid therapy.     

SUPPRESSION OF PERIOD DOUBLING CHATTER IN HIGH-SPEED MILLING BY SPINDLE SPEED VARIATION

Spindle speed variation is a well known technique to suppress regenerative machine tool vibrations, but it is usually considered to be effective only for low spindle speeds. In the current paper, spindle speed variation is applied to the high speed milling process, at the spindle speeds where the constant speed cutting results in period doubling chatter. The stability analysis of triangular and sinusoidal shape variations is made numerically with the semi-discretization method. It is shown that the milling process can be stabilized by increasing the amplitude of the spindle speed variation, while the frequency of the variation has no significant effect on the dynamic behaviour. The results are validated by experiments. Based on the analysis of the machined workpieces, it is shown that the surface roughness can also be decreased by the spindle speed variation technique.     

Water network cost optimization in a paper mill based on a new library of mathematical models

The increasing costs associated with water supply and the disposal of wastewater has stimulated industries to seek more efficient water management systems. Mathematical modelling and simulation can be a very valuable tool for the study of the multiple alternatives available whilst assessing optimum solutions for water management in industry. This study introduces a new steady state model library able to reproduce industrial water circuits. It has been implemented in a novel software framework for the representation, simulation and optimization of industrial water networks. A water circuit representing a paper mill has been modelled and simulated showing the capability to reproduce real case studies. Alternative scenarios for the water network have also been tested to assess the capability of the models to optimize water circuits minimizing total cost.     

Characteristics of WWTP sludge after drying in greenhouse for agricultural purposes

The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitória, Espírito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.     

Economic assessment of climate adaptation options for urban drainage design in Odense, Denmark

Climate change is likely to influence the water cycle by changing the precipitation patterns, in some cases leading to increased occurrences of precipitation extremes. Urban landscapes are vulnerable to such changes due to the concentrated population and socio-economic values in cities. Feasible adaptation requires better flood risk quantification and assessment of appropriate adaptation actions in term of costs and benefits. This paper presents an economic assessment of three prevailing climate adaptation options for urban drainage design in a Danish case study, Odense. A risk-based evaluation framework is used to give detailed insights of the physical and economic feasibilities of each option. Estimation of marginal benefits of adaptation options are carried out through a step-by-step cost-benefit analysis. The results are aimed at providing important information for decision making on how best to adapt to urban pluvial flooding due to climate impacts in cities.