High-speed Civil Transport Aircraft Emissions

Estimates are given for the emissions from a proposed high speed civil transport (HSCT). This advanced technology supersonic aircraft would fly in the lower stratosphere at a speed of roughly Mach 1.6 to 3.2 (470 to 950 m/sec or 920 to 1850 knots). Because it would fly in the stratosphere at an altitude in the range of 15 to 23 km commensurate with its design speed, its exhaust effluents could perturb the chemical balance in the upper atmosphere. The first step in determining the nature and magnitude of any chemical changes in the atmosphere resulting from these proposed aircraft is to identify and quantify the chemically important species they emit. Relevant earlier work is summarized, dating back to the Climatic Impact Assessment Program of the early 1970s and current propulsion research efforts. Estimates are provided of the chemical composition of an HSCT's exhaust, and these emission indices are presented. Other aircraft emissions that are not due to combustion processes are also summarized; these emissions are found to be much smaller than the exhaust emissions. Future advances in propulsion technology, in experimental measurement techniques, and in understanding upper atmospheric chemistry may affect these estimates of the amounts of trace exhaust species or their relative importance

Angular dependence of the magnetic-field driven superconductor-insulator transition in thin films of amorphous indium-oxide

A significant anisotropy of the magnetic-field driven superconductor-insulator transition is observed in thin films of amorphous indium-oxide. The anisotropy is largest for more disordered films which have a lower transition field. At higher magnetic field the anisotropy reduces and even changes sign beyond a sample specific and temperature independent magnetic field value. The data are consistent with the existence of more that one mechanism affecting transport at high magnetic fields.Comment: 4 pages, 5 figure

Graphene: Status and Prospects

Graphene is a wonder material with many superlatives to its name. It is the thinnest material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have the smallest effective mass (it is zero) and can travel micrometer-long distances without scattering at room temperature. Graphene can sustain current densities 6 orders higher than copper, shows record thermal conductivity and stiffness, is impermeable to gases and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a bench-top experiment. What are other surprises that graphene keeps in store for us? This review analyses recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.Comment: pre-edited version of the review published in Science Please note that only 40 references are allowed by the magazine. Sorr

Die beskerming van skuldeisers ingevolge artikel 34 van die Insolvensiewet na ’n skikkingsooreenkoms

Uit teks: Artikel 34 van die Insolvensiewet 24 van 1936 handel oor die nietige verkoop van ’n besigheid. Artikel 34(1) bepaal dat indien ’n handelaar ’n besigheid wat aan hom behoort, of die klandisie van so ’n besigheid, of goedere of eiendom wat ’n deel daarvan is, oordra ingevolge ’n kontrak (behalwe in die gewone loop van daardie besigheid of tot die versekering van die betaling van ’n skuld), en so ’n handelaar publiseer nie die kennisgewings wat in die artikel voorgeskryf word nie, dan is so ’n oordrag nietig teenoor sy skuldeisers vir ’n tydperk van ses maande na die oordrag en nietig teenoor die kurator van sy boedel indien sy boedel te enige tyd binne daardie ses maande tydperk gesekwestreer word. Vir hierdie doeleindes beteken “oordrag” ook die werklike of fiktiewe oordrag van besit: Die handelaar hoef dus nie fisies besit van die bedoelde goed aan die ander party oorgedra het nie (a 34(4)). Sodra ’n kennisgewing ingevolge artikel 34(1) gepubliseer word, word elke gelikwideerde skuld van die handelaar in verband met die bedoelde besigheid wat op ’n toekomstige dag invorderbaar sou word, dadelik invorderbaar as die betrokke skuldeiser betaling van die skuld eis (a 34(2))

Chaos and crises in a model for cooperative hunting: A symbolic dynamics approach

In this work we investigate the population dynamics of cooperative hunting extending the McCann and Yodzis model for a three-species food chain system with a predator, a prey, and a resource species. The new model considers that a given fraction sigma of predators cooperates in prey's hunting, while the rest of the population 1-sigma hunts without cooperation. We use the theory of symbolic dynamics to study the topological entropy and the parameter space ordering of the kneading sequences associated with one-dimensional maps that reproduce significant aspects of the dynamics of the species under several degrees of cooperative hunting. Our model also allows us to investigate the so-called deterministic extinction via chaotic crisis and transient chaos in the framework of cooperative hunting. The symbolic sequences allow us to identify a critical boundary in the parameter spaces (K, C-0) and (K, sigma) which separates two scenarios: (i) all-species coexistence and (ii) predator's extinction via chaotic crisis. We show that the crisis value of the carrying capacity K-c decreases at increasing sigma, indicating that predator's populations with high degree of cooperative hunting are more sensitive to the chaotic crises. We also show that the control method of Dhamala and Lai [Phys. Rev. E 59, 1646 (1999)] can sustain the chaotic behavior after the crisis for systems with cooperative hunting. We finally analyze and quantify the inner structure of the target regions obtained with this control method for wider parameter values beyond the crisis, showing a power law dependence of the extinction transients on such critical parameters

Gate-controlled Guiding of Electrons in Graphene

Ballistic semiconductor structures have allowed the realization of optics-like phenomena in electronics, including magnetic focusing and lensing. An extension that appears unique to graphene is to use both n and p carrier types to create electronic analogs of optical devices having both positive and negative indices of refraction. Here, we use gate-controlled density with both p and n carrier types to demonstrate the analog of the fiber-optic guiding in graphene. Two basic effects are investigated: (1) bipolar p-n junction guiding, based on the principle of angle-selective transmission though the graphene p-n interface, and (2) unipolar fiber-optic guiding, using total internal reflection controlled by carrier density. Modulation of guiding efficiency through gating is demonstrated and compared to numerical simulations, which indicates that interface roughness limits guiding performance, with few-nanometer effective roughness extracted. The development of p-n and fiber-optic guiding in graphene may lead to electrically reconfigurable wiring in high-mobility devices.Comment: supplementary materal at http://marcuslab.harvard.edu/papers/OG_SI.pd

An evaluation of metal removal during wastewater treatment: The potential to achieve more stringent final effluent standards

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2011 Taylor & Francis.Metals are of particular importance in relation to water quality, and concern regarding the impact of these contaminants on biodiversity is being encapsulated within the latest water-related legislation such as the Water Framework Directive in Europe and criteria revisions to the Clean Water Act in the United States. This review undertakes an evaluation of the potential of 2-stage wastewater treatment consisting of primary sedimentation and biological treatment in the form of activated sludge processes, to meet more stringent discharge consents that are likely to be introduced as a consequence. The legislation, sources of metals, and mechanisms responsible for their removal are discussed, to elucidate possible pathways by which the performance of conventional processes may be optimized or enhanced. Improvements in effluent quality, achievable by reducing concentrations of suspended solids or biochemical oxygen demand, may also reduce metal concentrations although meeting possible requirements for the removal of copper my be challenging

Isolation and purification of an enzyme hydrolyzing ochratoxin A from aspergillus niger

Ochratoxin A is a mycotoxin produced by several Aspergillus and some Penicillium species which may be present in food and feed products. It can be enzymatically hydrolyzed into ochratoxin α and l-β-phenylalanine, thereby decreasing its toxicity. The ochratoxin A degradation capacity of Aspergillus niger is well known and here we report the isolation and purification of a novel enzyme from A. niger that hydrolyzes this mycotoxin. A wheat germ medium supplemented with ochratoxin A was used to produce the enzyme, which was purified from culture filtrate by acetone precipitation and anion exchange chromatography. An overall purification of 2.5-fold with a recovery of 68% and a final specific activity of 36 U/mg was obtained. The enzyme is a metalloenzyme as it was inhibited at 10 mM EDTA, whereas PMSF had no effect. The ochratoxin A hydrolytic enzyme presented a V max of 0.44 μM/min and a K m of 0.5 mM when the reaction was carried out at pH 7.5 and 37°C.Fundação para a Ciência e a Tecnologia (FCT

Kernaspekte rondom die voeging van gades en vennote by 'n aansoek vir verpligte sekwestrasie

Core aspects pertaining to the joining of spouses and partners in an application for compulsory sequestration Joining parties as respondents in an application for compulsory sequestration is possible beyond instances where spouses are married in community of property or in cases involving partnerships. The practice in the Gauteng Division of the High Court is that several respondents are not allowed in a joint application for their individual sequestration, unless there is a complete identity of interests. The correctness of this established practice, as supported by the decision in Ferela (Pty) Ltd v Craigie and Others 1980 3 SA 167 (W) and Breetveldt and Others v Van Zyl and Others 1972 1 SA 304 (T), was drawn into question by the findings in Business Partners Ltd v Vecto Trade 87 (Pty) Ltd and Others 2004 5 SA 296 (SE) and Maree and Another v Bobroff and Another [2017] ZAGPJHC (7 March 2017), where the requirement of a “complete identity of interests” was substituted for a “substantial coincidence in the interests” of the respondents. With the 2017 decision in Strutfast (Pty) Ltd v Uys and Another 2017 6 SA 491 (GJ), there is a return to the former practice. The authors analyse this case and contend that it was correctly decided. However, the authors also draw attention to what the Strutfast case did not decide, and postulate that this implies that joining is also possible in alternative situations