Polymerization of liquid propylene with a fourth‐generation Ziegler–Natta catalyst: Influence of temperature,hydrogen, monomer concentration,and prepolymerization method on powder morphology

Liquid propylene was polymerized in a 5‐L autoclave batch reactor using a commercially available TiCl₄/MgCl₂/Al(ethyl)₃/DCPDMS Ziegler–Natta catalyst, with a phthalate ester as internal electron donor. The powders from these polymerizations were characterized using laser diffraction particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and bulk density measurements. These characteristics were analyzed as a function of the process conditions, including hydrogen and monomer concentration, polymerization temperature, and the prepolymerization method. It was shown that polymerization temperature influences the powder morphology to a large extent. At low temperatures, high‐density particles were obtained, showing regular shaped particle surfaces and low porosities. With increasing temperature, the morphology gradually was transferred into a more open structure, with irregular surfaces and poor replication of the shape of the catalyst particle. When using a prepolymerization step at a relatively low temperature, the morphology obtained was determined by this prepolymerization step and was independent from conditions in main polymerization. The morphology obtained was the same as that observed after a full polymerization at temperature. Even when using a short polymerization at an increasing temperature, the morphology was strongly influenced by the initial conditions. The effect of variation in hydrogen concentration supported the conclusion that the initial polymerization rate determines the powder morphology. In the absence of hydrogen, high bulk densities, and regularly shaped particles were obtained, even at high temperatures. With increasing hydrogen concentration, the reaction rates increased rapidly, and with that changed the morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1421–1435, 2003     

Multi-dimensional regional inequality as an alternative allocation mechanism For EU Structural Funds remittances: The case of Spain and Hungary

We propose a multidimensional approach to regional inequality as an alternative allocation mechanism for EU Structural Funds remittances based on per capita GDP, particularly after EU enlargement. The indicators of regional inequality are combined to a composite index by means of Maasoumi's aggregator function. We propose Partial Common Principal Component Aanalysis as the estimator of the weights for the aggregator function. Application of the multidimensional approach to Spain shows that there are substantial differences between the rankings of the regions obtained by means of the multidimensional approach and the traditional approach based on per capita GDP. For Hungary, which is less developed than Spain, the rankings differ less.     

Dekker's mutual exclusion algorithm made RW‐safe

Dekker's algorithm was thought to be safe in an environment without atomic reads or writes where bits flicker or scramble during simultaneous operations. A counter‐example is presented showing Dekker's algorithm is unsafe without atomic read. A modification to the original algorithm is presented making it RW‐safe, allowing threaded systems to be built on low cost/power hardware without atomic read/write. Correctness is verified by means of invariants and UNITY logic. A performance comparison is made for several two‐thread software mutual‐exclusion algorithms to see if the RW‐safe Dekker is competitive. A subset of the two‐thread solutions are then compared in two N‐thread tournament algorithms. The performance results show that the additional checks in the RW‐safe Dekker do not disadvantage the algorithm in comparison with other two‐thread algorithms. The RW‐safe N‐thread tournament algorithms are competitive with the hardware‐assisted Mellor‐Crummey and Scott algorithm. Copyright © 2015 John Wiley & Sons, Ltd.     

Consumer implications of the WCRF's permanent update on colorectal cancer

The last update published by the World Cancer Research Fund on colorectal cancer shows that there is convincing evidence that physical activity could contribute to the prevention of this type of cancers, while highlighting red meat and meat products consumption and alcohol among the factors that increase the disease's risk. The main message of this document is that the best prevention of colorectal cancer is the combination of higher physical activity with a fibre-rich and meat products poor diet. This information is useful the consumer who should make his food choices according to the scientific evidence. This contribution highlights challenges in communication and possible effects from the consumer perspective.     

Strategies to optimize phosphate removal from industrial anaerobic effluents by magnesium ammonium phosphate (MAP) production

BACKGROUND: Owing to more stringent phosphate discharge requirements and the increasing prices of fertilizers, beneficial recovery and reuse of phosphate from industrial anaerobic effluents is becoming an important issue. Phosphate recovery by struvite or magnesium ammonium phosphate (MAP) permits its recycling in the fertilizer industry because struvite is a valuable slow release fertilizer. Two different approaches to MAP crystallization depending on initial levels of phosphate in the wastewaters were tested and compared. RESULTS: For low‐phosphate‐containing anaerobic effluents (<30 mg PO₄^3?‐P L^?1), a novel approach using ureolytic induced MAP formation with MgO addition appeared to be suitable. The residual phosphate concentrations in the effluent ranged from 5 to 7 mg PO₄^3?‐P L^?1 and the separated matter contained residual amounts of Mg(OH)₂. High‐phosphate‐containing anaerobic effluents (100 to 120 mg PO₄^3?‐P L^?1) were treated efficiently using air stripping combined with MgCl₂ and NaOH reagents, yielding residual phosphate levels of 8 to 15 mg PO₄^3?‐P L^?1 and spherical pure MAP crystals of 0.5 to 2 mm. CONCLUSION: Results show that depending on the initial phosphate concentrations in the wastewaters and the ammonium and magnesium levels, the strategy selected for struvite crystallization is a determinative factor in achieving a cost effective technology. Copyright © 2008 Society of Chemical Industry     

Structure and phase behavior of a disk-necklace polymer: Cyclolinear polymethylsiloxane

The structure and phase transitions of cyclolinear polyorganosiloxane copolymer containing 12-member polysiloxane rings have been studied using synchrotron WAXS, DSC, TEM, variable-temperature AFM and polarized optical microscopy. The primary structure of this polymer can be viewed as a necklace of disk-shaped entities (cyclic groups) connected via flexible linkers.In the mesomorphic state, the presence of two different LC phases has been derived from the analysis of WAXS fiber diffractograms. The morphology of one of the phases shows a conventional hexagonal packing of LC chains where the chain axes are perpendicular to the plane of the 2D hexagonal lattice. The other one, so-called R-phase, has a vertically oriented rectangular 2D lattice formed by inter-chain correlations between the bulky polysiloxane cycles (disks). To our knowledge, such a disk-necklace mesophase in which the LC lattice is parallel to the backbone direction has not been reported in the literature so far.     

Pragmatic software tools for water reuse evaluation in a factory

The optimal use of process water becomes increasingly important since natural water resources are heavily solicited by a growing economy. Two steps can be considered in the process water optimization. A first step is the inventory of the different process streams in the process water network. Pure mathematical modeling of a dynamic water network is extremely complicated and expensive. As an approximation, the use of a steady-state network node model within commercial software is accepted to set up a water balance. Sophisticated software tools are available but common solver software may offer an alternative. A second step is the water “pinch” which searches for an optimal use of process water by combining sources and sinks, taking into account contaminant concentrations of process streams. Sophisticated pinch software can be applied but it is also possible to implement a simplified combinatory approach. Such approach can be pragmatically programmed in e.g., Visual Basic. Such tool allows for a first evaluation of the complex combinatory sources–sinks problem, enabling a low cost and easy-to-handle first interpretation of possible water-reuse opportunities. This could stimulate a further enhanced analysis with more advanced software tools and therefore promote a sustainable use of process water in the industrialized world.     

数字化回传技术

对于有线电视运营商来说，为满足当今快速增长的语音和高速数据业务的需要．双向通信系统中的“上行”回传就显得尤为重要。最初的“广播”网中，回传通道只局限于对覆盖用户的状态监控和基本的机顶盒控制，随着时间的推进，情况逐步发生变化：先是受限机顶盒交互的QPSK调制，然后是DOCSIS 1．x的16QAM调制,再到DOCSIS2．0和DOCSIS3．0的64QAM调制。     

Exploration and Exploitation in Innovation: Reframing the Interpretation

There has been a burgeoning literature about exploitation and exploration since March's seminal article in 1991. However, in reviewing the extant literature we find different interpretations of both concepts leading to ambiguity and even some inconsistency. This paper focuses in particular on the interpretation of exploration and exploitation in the literature on technological innovation. It addresses two critical research questions. First, what are the different interpretations of exploitation and exploration? Second, how can we set up a framework that reconciles these differences and reduces the ambiguity that we find in the literature? To answer these two questions, we first explain what the root causes of these different viewpoints are. Second, we provide a theoretical framework that integrates the different perspectives, sets up a new typology to define exploration and exploitation, identifies white spaces in the current research and provides guidance for future research.