Degradation of drag-reducing polymers

A simple, fixed-head flow device was used to characterize drag reduction by polymers in water. Using a parallel flow of water as a reference system, the Reynolds numbers ranged from 8600 to 12,000. The degradation of poly(ethylene oxide) and polyacrylamide during turbulent flow of dilute solutions (1 to 50 g/kl) was measured in terms of friction-reducing effectiveness. Poly(ethylene oxide) decreases in effectiveness more rapidly than polyacrylamide in a recycling test.     

Bioassays and the algal populations of Hastings Lake, Alberta, Canada

During summer 1978 an analysis was made of the biomass development and algal species composition of Hastings Lake, a shallow eutrophic lake near Edmonton, Alberta, Canada. The algal growth potential of Hastings Lake water during the period of investigation was of particular interest. Bioassays were carried out using untreated water, water inoculated with Anabaena flos-aquae (competition experiments) and filtered or autoclaved water.The results of bioassays with untreated Hastings Lake water were well correlated with the biomass development in the lake. Bioassays with unialgal cultures in filtered or autoclaved water were carried out to obtain information concerning the nutrient situation in the lake. Iron and/or phosphorus appear to be important limiting factors during the summer period in Hastings Lake.     

Passive Temperature-Compensating Technique for Microstructured Fiber Bragg Gratings

The thermal drift of the characteristic wavelength of fiber Bragg gratings (FBGs) photowritten in the core of microstructured fibers (MOFs) is significantly reduced by inserting a liquid of suitable refractive index into their holes. For instance, the spectral range of variations is divided by a factor of 4 over a temperature range larger than 20degC in a six-hole MOF, and the maximum sensitivity is reduced. Such passive FBG temperature compensation technique is of great interest for applications involving accurate sensing free of thermal effects.     

Use of monod kinetics on multi-stage bioreactors

At present, the alternatives of constructing either large units in biological waste water treatment plants (in this case single-stage activated sludge basins) or a few smaller units—either multi-stage reactors or reactors connected in series, is gaining more and more importance. In West Germany, in a recent workshop dedicated to this subject, it became evident that the knowledge of the significance of volume and/or sludge loads gained in decades of operating single-stage activated sludge tanks cannot readily be applied to multi-stage units. By extending the Monod reaction kinetics model for enzyme-substrate reactions a process analysis is carried out for a series-connection of up to four CSTR (completely stirred reactors) and the author presents a few graphical solutions to characterize and design a cascade-connected system.     

Crystallography of the Directionally Solidified NiO-Gd2O3 Eutectic

Crystallographic relations between the two phases of the eutectic in the system NiO-Gd₂O₃ were determined by X-ray diffraction and optical microscopy. A model of the atomic arrangement at the phase interface is proposed.     

Untersuchungen zum Kristallisationsverhalten von Schlacken

Chemische und physikalische Vorgänge beim Abkühlen von Schlacken unterschiedlicher Viskosität. Berechnung des zeitlichen Abkühlungsverlaufes in einer Schlackenschicht. Simulierung der erhaltenen Kurven in Laboratoriumsversuchen. Allgemeingültige Aussagen über die Abhängigkeit des glasigen oder kristallinen Anteils in Schlacken von deren Zähigkeit und Schichtdicke.     

Adiabatic polymerization of acrylamide using a persulfate–bisulfite redox couple

The temperature rise during the adiabatic polymerization of acrylamide in water has been used to characterize the kinetic parameters. Based on initial rate data, the following equation is obtained: where concentrations of monomer, persulfate, and bisulfite are in mole/kg, T is in K, and t is in min. The order with respect to monomer is confirmed by an analysis of the entire temperature–time record during polymerization. The persulfate–bisulfite couple was studied also in the absence of monomer. Concentrations were measured by UV absorbance and by permanganate titration. The reaction can be represented by: where concentrations are in mole/liter, T is in K, and t is in min.     

Heat sealing of semicrystalline polymer films. II. Effect of melting distribution on heat-sealing behavior of polyolefins

Heat sealing of films, i. e., formation of a joint between two films by placing them fleetingly between heated platens, was experimentally investigated for a variety of semicrystalline polyolefins, especially various polyethlenes, to determine how sealing temperature affected seal strength measured at room temperature. Seal strength as a function of sealing temperature, SS(T), is closely related to the melting distribution of the polymer determined by DSC measurements, i. e., to the fraction of amorphous phase as a function of temperature, f_a(T). Seal initiation temperature, the temperature at which a specific, low level of seal strength of polyethylene films is achieved, corresponds to the temperature at which the fraction of amorphous phase equals 77±3%. At higher temperatures, SS(T) increases approximately as f_a(T) increases. At the final melting point of the polymer, i.e., when f_a(T) =1, seal strength reaches an approximately constant value termed the plateau seal strength. The magnitude of the plateau seal strength is determined by the yield stress of the polymer film. Thus, the heat-sealing curve, SS(T), for a polyethylene can be semiquantitatively predicted from the melting distribution and yield stress of the polymer. © 1994 John Wiley & Sons, Inc.     

创建有效的解决方案：从过程的角度出发

Global competition and declining margins have made enterprises in diverse industries increasingly aware that assuring low cost, product performance and high quality is no longer sufficient for long-term success. Integrating products and services to customized solutions can help firms to differentiate from their competitors. Based on 11 in-depth interviews with managers from solution providers and an exploratory survey with 45 solution providers we derive a four-step process of value creation as well as a set of critical activities and pitfalls within each step. Selling solutions require customer-supplier relational processes comprising analysis/consulting, design/configuration, implementation/delivery, and support/operation. To get a better understanding of the relational process we adopted this perspective on creating solutions in order to identify crucial routines and activities. Two main capabilities within this process can be identified: customer interaction and project management. Both capabilities are required in order to deliver more effective solutions at profitable prices.     

Quantifying and comparing the selectivity for crosslink scission in mechanical and mechanochemical devulcanization processes

Devulcanization processes have potential to increase the economic value of ground tire rubber (GTR) derived from waste tires, although the chemistry of the devulcanization process is still poorly understood. This article presents a method, based on sol extraction and swelling measurements, for quantifying the selectivity for crosslink scission over main chain scission, and applies it to extrusion‐based mechanical and mechanochemical devulcanization processes at various operating conditions. The mechanochemical devulcanization process, using diphenyl disulfide and process oil, resulted in a higher selectivity for crosslink scission than the mechanical devulcanization process. Furthermore, it was shown that the process oil, along with lower reaction temperature, in the mechanochemical devulcanization process was responsible for the increased selectivity, rather than the presence of diphenyl disulfide. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43932.