Charting the Potential of Landscape Urbanism in Dubai

Landscape Urbanism has been, to date, a theory emerging primarily from the Western world. This paper counters the Western focus by exploring the potential of Landscape Urbanism theory in Dubai. In a previous article published by the author, landscape architecture in Dubai has been identified as diverging from the tenets of the various charters of the International Federation of Landscape Architects (IFLA), having apparently scant regard for pressing ecological, social and cultural design issues. Landscape Urbanism in this paper is discussed with respect to its ability to bolster the practice of landscape architecture in Dubai in relation to these issues. The paper argues that a number of key facets of Landscape Urbanism appear difficult to reconcile with the ecological, social and cultural conditions of Dubai. Further to this, it tends to lack the tools by which landscape urbanists in Dubai could link theory with practice.     

有机硅BS94对以脱硫石膏为原料生产的耐水纸面石膏板性能的影响

探讨了不同掺量的有机硅BS94对脱硫石膏吸水率、抗折强度、抗压强度、初凝时间、终凝时间的影响规律,分析了脱硫石膏中杂质对有机硅BS94防水性能的影响。结果表明,有机硅BS94对以脱硫石膏为原料生产的耐水纸面石膏板具有较好的防水性能,可以广泛应用于以脱硫石膏生产耐水纸面石膏板的工艺中,但当脱硫石膏中的F离子含量较高时,防水剂的防水性能会有所下降,因此,应严格控制原料中可溶性F的含量。     

Towards Effective City Planning—The Case of Cape Town in Identifying Potential Housing Land

Vacant land in cities is an important resource as it presents opportunities for urban renewal and revitalisation and can contribute to municipal revenue. In a context of growing informality and homelessness in cities of the South, the presence of large tracts of vacant land is a sign of inefficient urban planning and a dysfunctional land market. It is therefore critical for local governments to have reliable data of the extent of vacant land parcels in cities and their potential for housing development, particularly affordable housing for the poor. This paper will detail and discuss the “Potential Housing Land Model” developed by the Cape Urban Observatory, part of the African Centre for Cities, based at the University of Cape Town, South Africa. South African cities, and in this case the city of Cape Town in particular, face huge constraints in terms of suitable, well-located and affordable land for low-cost housing development. A tool like the “Potential Housing Land Tool” is one tool which could assist decision-makers in identifying such land parcels. Besides identifying land that can potentially be used for housing; the model can also allow officials to pin-point areas that are not well-serviced. The deployment of the model on the World Wide Web makes the tool available to a range of users including municipal officials, academic researchers and organised sectors of civil society who might benefit from this kind of information. The responsible and strategic use of this model and the information it provides, can facilitate a broad-based discussion about vacant land and its potential use in the city, allowing for more transparent and participatory planning. The application of tools like the “Potential Housing Land Tool” can therefore greatly assist in improving urban governance and can contribute towards more efficient and sustainable urban planning and management systems.     

The effect of sodium polymethacrylate on the rheology of the positive paste and performance of the lead-acid battery

Due to its rheological properties, positive lead-acid battery paste can be difficult to spread on lead current collectors accurately and efficiently under industry machinery and setting. Sodium polymethacrylate dispersant was studied as an effective positive paste additive that could lower the yield stress of the paste without affecting paste density and battery performance. Under a four-blade vane rheometer setup, stress growth and oscillatory amplitude strain sweep experiments evaluated the rheological properties of positive paste with the addition of varying amounts of sodium polymethacrylate. Further, the electrochemical effects of sodium polymethacrylate were also evaluated in 2V batteries by testing positive active material utilization and cycle life.     

Flash Sintering of Nanocrystalline Zinc Oxide and its Influence on Microstructure and Defect Formation

We report the sintering behavior of nanocrystalline zinc oxide under external AC electric field between 0 and 160 V/cm. In situ acquisition of density by means of laser dilatometry, evaluation of specimen temperature, real‐time measurement of electric field and current help analyze this peculiar behavior. Field strength and blocking electrodes significantly affect densification and microstructure, which was evaluated in the vicinity of the flash event and for the fully sintered material. High current densities flow through the sample at high electric fields, entailing a sudden increment of the temperature estimated to several hundreds of K and an exaggerated grain growth. In contrast, low current density flows through the sample at lower electric fields, which guarantees normal grain growth and highest final density. Macroscopic photoluminescence measurements give insights into the development of the defect structure. Electric fields are expected to enhance defect mobility, explaining the high densification rates observed during the sintering process.     

Coarse-Grained and Atomistic MD Simulations of RNA and DNA Folding

Although the main features of the protein folding problem are coming into clearer focus, the microscopic viewpoint of nucleic acid folding mechanisms is only just beginning to be addressed. Experiments, theory, and simulations are pointing to complex thermodynamic and kinetic mechanisms. As is the case for proteins, molecular dynamics (MD) simulations continue to be indispensable tools for providing a molecular basis for nucleic acid folding mechanisms. In this review, we provide an overview of biomolecular folding mechanisms focusing on nucleic acids. We outline the important interactions that are likely to be the main determinants of nucleic acid folding energy landscapes. We discuss recent MD simulation studies of empirical force field and Go-type MD simulations of RNA and DNA folding mechanisms to outline recent successes and the theoretical and computational challenges that lie ahead.     

Association Colloids Formed by Multiple Surface Active Minor Components and Their Effect on Lipid Oxidation in Bulk Oil

Association colloids formed by surface active minor components play an important role in the oxidative stability of bulk oils. To imitate the formation of nanostructures in refined oils, multiple surface active minor components including phospholipids, free fatty acids, diacylglycerols and sterols were added to stripped corn oil. The critical micelle concentration (CMC) of the mixed components was determined. The impact of mixed minor components at below and above their CMC on oxidative stability of bulk oil and on antioxidant activity of α-tocopherol and Trolox was investigated. The CMC of the mixed surface active components in bulk oil was 20 µmol/kg oil in the presence of 383 ± 2 ppm of water. 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) played an important role on the formation of association colloids since it was the most important component in forming the association colloids as confirmed by CMC and fluorescence probe studies. The association colloids formed by the mixed components showed prooxidative activity in bulk oil as determined by monitoring the formation of lipid hydroperoxide and hexanal. The activity of α-tocopherol or Trolox was not changed by mixed components association colloids. These results suggest that association colloids both physically and chemically impacted the oxidative stability and activity of antioxidants in bulk oil.     

Impact of Phosphoethanolamine Reverse Micelles on Lipid Oxidation in Bulk Oils

Phospholipids are important minor components in edible oil that play a role in lipid oxidation. Surface active phospholipids have an intermediate hydrophilic–lipophilic balance value, which allows them to form association colloids such as reverse micelles in bulk oil. These association colloids can influence lipid oxidation since they create lipid–water interfaces where prooxidants and antioxidants can interact with triacylglycerols. In this study, we examined the formation of reverse micelles in a stripped oil system by dioleoyl phosphoethanolamine (DOPE) and the effect of these physical structures on lipid oxidation kinetics. The critical micelle concentration (CMC) of DOPE was approximately 200 µmol/kg oil at 45 °C. Oxidation kinetics studies showed that DOPE was prooxidative when it was above its CMC (400 and 1,000 µM), reducing the lag phase from 14 days (control) to 8 days. The addition of combinations of DOPE and dioleoyl phosphocholine (DOPC) resulted in formation of mixed micelles with a CMC of 80 µmol/kg oil at 45 °C. These mixed micelles were also prooxidative when concentrations (100 and 500 µM) were above the CMC, decreasing the lag phase from 14 to 8 days. These findings provide a better understanding of the role of phospholipids in lipid oxidation of edible oil and could contribute to better antioxidant solutions.