Case of escape in cassava, Manihot esculenta Crantz

Two cassava escapes where collected from cultivated fields near natural habitat in Bolivia. They are described morphologically and analyzed cytogenetically in this study. It is suggested that they are the product of backcrosses of cassava interspecific hybrids with the cultigen itself, and that selective conditions have developed in which certain forms of cassava segregates have adapted to grow wildly in natural habitats near cassava fields. These segregates may hybridize with cultivated cassava upon coming in contact with such varieties. Because these escapes have incorporated useful genes from the wild into their genetic structure, they could be used for cassava improvement since their genetic barriers with other forms of cassava are very weak

An unbiased and efficient assessment of excitability of sensory neurons for analgesic drug discovery

Alleviating chronic pain is challenging, due to lack of drugs that effectively inhibit nociceptors without off target effects on motor or central neurons. Dorsal root ganglia (DRG) contain nociceptive and non-nociceptive neurons. Drug screening on cultured DRG neurons, rather than cell lines, allows the identification of drugs most potent on nociceptors with no effects on non-nociceptors (as a proxy for unwanted side effects on CNS and motor neurons). However, screening using DRG neurons is currently a low-throughput process and there is a need for assays to speed this process for analgesic drug discovery. We previously showed that veratridine elicits distinct response profiles in sensory neurons. Here we show evidence that a veratridine-based calcium assay allows an unbiased and efficient assessment of a drug effect on nociceptors (targeted neurons) and non-nociceptors (non-targeted neurons). We confirmed the link between the oscillatory profile and nociceptors; and the slow-decay profile and non-nociceptors using three transgenic mouse lines of known pain phenotypes. We used the assay to show that blockers for Nav1.7 and Nav1.8 channels, which are validated targets for analgesics, affect non-nociceptors at concentrations needed to effectively inhibit nociceptors. However, a combination of low doses of both blockers had an additive effect on nociceptors without a significant effect on non-nociceptors, indicating that the assay can also be used to screen for combinations of existing or novel drugs for the greatest selective inhibition of nociceptors

Microgrid Enabling Towards the Implementation of Smart Grids

Smart grids have emerged as dominant platforms for effectively accommodating high penetration of renewable-based distributed generation (DG) and electric vehicles (EVs). These smart paradigms play a pivotal role in the advancement of distribution systems and pave the way for active distribution networks (ADNs). However, the large number of smart meters deployed in the distribution system (e.g., 200 million smart meters will be installed in Europe by 2020) represents one of the main challenges facing the management and control of distribution networks and thus the enabling of smart grids. In addition to the data tsunami flooding central controllers, the concerns about privacy and system vulnerability are fast becoming a key restraint for the implementation of the smart grids. These concerns are prompting utilities to be more reluctant to adopt new techniques, leaving the distribution system mired in relatively old-fashioned routines. Microgrids provide an ideal paradigm to form smart grids, thanks to their limited size and ability to ‘island’ when supplying most of their loads during emergencies, which improves system reliability. However, preserving load-generation balance is comprehensively challenging, given that microgrids are dominated by renewable-based DGs, which are characterized by their probabilistic nature and intermittent power. Although microgrids are now well-established and have been extensively studied, there is still some debate over having microgrids that are solely ac or solely dc, with the consensus tending toward hybrid ac-dc microgrids. Furthermore, while some research has addressed using solely ac microgrids, the planning of hybrid ac-dc microgrids has not yet been investigated, despite the many benefits these types of microgrids offer. Additionally, developing steady-state analysis tools capable of handling grid-connected mode and islanded mode for the operation of ac microgrids and hybrid ac-dc microgrids still has uncertainties about their computational burden, complexity, and convergence. The high R/X ratio characterized distribution systems result in ill-condition that hinders the convergence of conventional Newton Raphson (NR) techniques. Moreover, calculating the inversion of the Jacobian matrix that is formed from the calculation of derivatives adds to the complexity of these techniques. Therefore, developing a simple, accurate, and fast steady-state analysis tool is crucial for enabling microgrids and hence smart grids. Driven by the aforementioned challenges, the broad goal of this thesis is to enable microgrids as building clusters to smooth and accelerate the realization of smart grids. Achieving this objective involves a number of stages, as follows: 1) The development of probabilistic models for loads and renewable DG-based output power. These models are then integrated with the load flow analysis techniques to form a probabilistic power flow (PPF) tool. 2) The proposal of a novel operational v philosophy that divides existing bulky grids into manageable clusters of self-adequate microgrids that adapt their boundaries to keep load-generation balance at different operating scenarios. 3) The proposal of planning a framework for the newly constructed grids as hybrid ac-dc microgrids with minimum levelized investment costs and consideration of the probabilistic nature of load and renewable generation. 4) The development of a branch-based power flow algorithm for steady-state analysis of ac microgrids and hybrid ac-dc microgrids

Virtual Wireless and Mobile Communication Laboratory

Creating a virtual laboratory for distance learning courses has become recently so important recently for engineering education. In this paper, we provide a full description for a remote access technique used in a wireless and mobile communication laboratory. Hence, the student will be able to perform experiments online and controlling and watching the devices by accessing a camera already built in the laboratory. Signal generator, spectrum analyzer and field-fox devices are used in the virtual laboratory.https://doi.org/10.5923/j.edu.20120201.0

Improving the voltage quality of Abu Hummus network in Egypt

In this paper the performance of the electrical network of Egypt is studied by considering a small part on the network (Abu Hummus city). The transmission network of Abu Hummus city was created for 66 kV, 11 kV, and 0.4 kV in the digital simulation and electrical network calculation (DIgSILENT power factory software) to study the voltage profiles. The load flow operational analysis was performed to obtain the voltage magnitudes at every bus bar. The voltage magnitudes in 11 kV and 0.4 kV networks were 10% to 15% less than the nominal value due to overloading off the transmission lines and the voltage magnitudes in 66 kV was within permissible limits. By using automatic tap-changing transformer or Static VAR System, the main idea of this paper is to obtain the voltage profiles at every bus bar to improve the voltage quality of the networks, so as to achieve better voltage profiles on the low voltage side without much effect on high voltage side under various operating conditions

Cytogenetics and evolution of cassava (Manihot esculenta Crantz)

All Manihot species so far examined, including cassava (Manihot esculenta), have 2n = 36. Interspecific hybrids between cassava and its wild relatives show fair regular meiosis, and backcrossed generations exhibit high fertility. Electrophoresis shows affinity between species of different sections, as well as between some of them and cassava itself. Polyploidy has apparently contributed to the rapid speciation of this genus, while apomixis has offered a means of perpetuating new hybrid types adapted to different environments. It is assumed that cassava originated by hybridization between two wild Manihot species followed by vegetative reproduction of the hybrid

Photochemical generation of a viable oxidizing agent and application to dye photobleaching

PhD ThesisMolecular photochemistry is a well-established branch of science that owes its origins to the pioneering studies of Alexander Schönberg in Egypt during the 1940’s and 50’s. The main advantage of photochemistry relies on the use of sunlight to drive “difficult” reactions, the most important being the production of molecular oxygen and chemical fuel by way of natural photosynthesis. While photovoltaic cells and systems based on inorganic semiconductors have developed enormously during the past few decades, there have been few comparable advances in molecular photochemistry. This is despite the ready availability of powerful spectroscopic and computational tools. Indeed, the mantle of “artificial photosynthesis” has been transferred from chlorophyll derivatives to silicon and its allies. In this thesis, we explore the concept of developing simple photochemical means to drive oxidative processes that might be both practical and costeffective. Several systems are considered and subjected to experimental study. Chapter 1 presents a general introduction to the field and illustrates both the potential and the frustration offered by molecular photochemistry. Typical excited state reactions are described in terms of simple molecular orbital diagrams. The discussion is directed towards dye photobleaching; a topic of considerable contemporary significance given the recent advances in single-molecule fluorescence and super-resolution microscopy. Ways to protect dyes against the deleterious effects of exposure to laser light are reviewed and common reactive intermediates are identified. The introduction provides background information for the subsequent research work. Experimental protocols for monitoring the course of dye photofading are introduced. This chapter is followed by an account of the experimental practices followed during our work. Chapter 2 includes a description of the methods used for data analysis. Chapter 3 recognises the need to generate a relatively stable intermediate oxidant if a viable photobleaching strategy is to be devised. Most of the intermediates generated under illumination survive for periods of a few microseconds or less and therefore require high concentrations of substrate to ensure chemical trapping before deactivation. The approach suggested involves the photochemical production of an organic hydroperoxide that is sufficiently stable to be characterised by NMR spectroscopy. The bleaching capability of this species is assessed by 1 specific reference to the decolouration of indigo. The latter is a popular dye that displays exceptional stability towards sunlight. Chapter 4 continues this theme by examining the photobleaching of methylene blue (MB) in water. This cationic dye is known to bleach quickly on exposure to visible light and we have studied the mechanism and efficacy of the bleaching reaction. The importance of light intensity and dissolved oxygen are stressed. The key discovery made here relates to the ability of high concentrations of urea to inhibit photochemical bleaching of MB. This is a surprising result that offers promise for providing protection for oxidative damage of certain dyes. The mechanism by which urea operates has been deduced by way of kinetic measurements. Chapter 5 looks at the catalysed bleaching of a novel strapped boron dipyrromethene (BODIPY) derivative. This dye represents a new type of BODIPY dye that displays circularly polarised luminescence. Direct and catalysed photobleaching processes are compared and the importance of dissolved oxygen is assessed. The dye has a highly strained geometry imposed by the straps attached to the boron atom. Oxidation can help relieve this steric strain. Chapter 6 takes a different perspective and enquires if chlorine dioxide can be generated by photochemical protocols. Chlorine dioxide is an important bleach but is not in common use because it is difficult to manufacture in bulk and has limited stability on storage. In principle, it should be possible to generate chlorine dioxide by photochemical means. This could provide access to a powerful antiseptic reagent in remote locations using sunlight as the only energy input. Several putative ways to produce chlorine dioxide are considered and an analytical protocol is devised for quantitative determination. It is concluded that a practical set-up could be engineered for the in-situ production of chlorine dioxide in aqueous solution.Umm Al-Qura University as represented via Saudi Embass

Wild cassava, Manihot spp. : biology and potentialities for genetic improvement

Espécies selvagens de Manihot dão origem à mandioca. Elas constituem valioso reservatório genético, com genes mostrando novos caracteres. O exame cuidadoso dessas espécies mostrou que algumas delas têm uma percentagem notavelmente alta de proteína combinada com uma porcentagem baixa de ácido cianídrico. O estudo dos habitats naturais revelou resistência à seca e à toxicidade por alumínio em excesso no solo, assim como adaptação a baixas temperaturas. Alguns dos híbridos obtidos mostraram alta produtividade da raiz e resistência a brocas do caule. A apomixia foi descoberta nas espécies selvagens e transferida com sucesso para as espécies cultivadas.Wild species of Manihot are progenitors of cassava. They constitute valuable genetic reservoirs presenting genes that show new characters. Screening of these species showed some of them to have a notably high percentage of protein combined with a low percentage of hydrocyanic acid. Study of natural habitats revealed resistance to drought and excessive soil aluminum toxicity as well as adaptation to low temperature. Some of the hybrids obtained showed high root productivity and resistance to stem borers. Apomixis was discovered in the wild and transferred successfully to the cultivate species