Test apparatus for locating shorts during assembly of electrical buses

A test apparatus is described for locating electrical shorts that is especially suited for use while an electrical circuit is being fabricated or assembled. A ring counter derives input pulses from a square wave oscillator. The outputs of the counter are fed through transistors to an array of light emitting diodes. Each diode is connected to an electrical conductor, such as a bus bar, that is to be tested. In the absence of a short between the electrical conductors the diodes are sequentially illuminated. When a short occurs, a comparator/multivibrator circuit triggers an alarm and stops the oscillator and the sequential energization of the diodes. The two diodes that remain illuminated identify the electrical conductors that are shorted

Complex permeability of soft magnetic ferrite polyester resin composites at frequencies above 1 MHz

Composite soft magnetic materials consist of magnetic particles in a non-magnetic matrix. The properties of such materials can be modelled using effective medium theory. Measurements have been made of the complex permeability of composites produced using ferrite powder and polyester resin. The success of various effective medium expressions in predicting the variation of complex permeability with composition has been assessed

Measurements of magnetic circuit characteristics for comprehension of intrinsic magnetic properties of materials from surface inspection

A transfer function is presented for calculating magnetic field and flux density inside a test material as a result of surface measurement. By considering flux leakage, we introduce a parameter η, called the leakage coefficient, which can be experimentally determined. It is introduced into the equations to make the transfer function more practical. The distribution of field inside a test material is then discussed in accordance with a surfacemagnetic charge model

Using adult mosquitoes to transfer insecticides to Aedes aegypti larval habitats.

Vector control is a key means of combating mosquito-borne diseases and the only tool available for tackling the transmission of dengue, a disease for which no vaccine, prophylaxis, or therapeutant currently exists. The most effective mosquito control methods include a variety of insecticidal tools that target adults or juveniles. Their successful implementation depends on impacting the largest proportion of the vector population possible. We demonstrate a control strategy that dramatically improves the efficiency with which high coverage of aquatic mosquito habitats can be achieved. The method exploits adult mosquitoes as vehicles of insecticide transfer by harnessing their fundamental behaviors to disseminate a juvenile hormone analogue (JHA) between resting and oviposition sites. A series of field trials undertaken in an Amazon city (Iquitos, Peru) showed that the placement of JHA dissemination stations in just 3-5% of the available resting area resulted in almost complete coverage of sentinel aquatic habitats. More than control mortality occurred in 95-100% of the larval cohorts of Aedes aegypti developing at those sites. Overall reductions in adult emergence of 42-98% were achieved during the trials. A deterministic simulation model predicts amplifications in coverage consistent with our observations and highlights the importance of the residual activity of the insecticide for this technique

The ephemerides of the Earth-Moon barycenter, Venus, Mars, and Mercury considering the Earth and Moon as separate bodies

Ephemerides of Earth-Moon barycenter, Venus, Mars, and Mercury considering Earth and Moon as separate bodie

Chemically Oscillating Reactions during the Diagenetic Formation of Ediacaran Siliceous and Carbonate Botryoids

Chemically oscillating reactions are abiotic reactions that produce characteristic, periodic patterns during the oxidation of carboxylic acids. They have been proposed to occur during the early diagenesis of sediments that contain organic matter and to partly explain the patterns of some enigmatic spheroids in malachite, phosphorite, jasper chert, and stromatolitic chert from the rock record. In this work, circularly concentric self-similar patterns are shown to form in new chemically oscillating reaction experiments with variable mixtures of carboxylic acids and colloidal silica. This is carried out to best simulate in vitro the diagenetic formation of botryoidal quartz and carbonate in two Ediacaran-age geological formations deposited after the Marinoan–Nantuo snowball Earth event in South China. Experiments performed with alkaline colloidal silica (pH of 12) show that this compound directly participates in pattern formation, whereas those with humic acid particles did not. These experiments are particularly noteworthy since they show that pattern formation is not inhibited by strong pH gradients, since the classical Belousov–Zhabotinsky reaction occurs in solu-tion with a pH around 2. Our documentation of hundreds of classical Belousov–Zhabotinsky experiments yields a number of self-similar patterns akin to those in concretionary structures after the Marinoan–Nantuo snowball Earth event. Morphological, compositional, and size dimensional com-parisons are thus established between patterns from these experiments and in botryoidal quartz and carbonate from the Doushantuo and Denying formations. Selected specimens exhibit circularly concentric layers and disseminations of organic matter in quartz and carbonate, which also occurs in association with sub-micron-size pyrite and sub-millimetre iron oxides within these patterns. X-ray absorption near edge structure (XANES) analyses of organic matter extracted from dolomite concretions in slightly younger, early Cambrian Niutitang Formation reveal the presence of carboxylic and N-bearing molecular functional groups. Such mineral assemblages, patterns, and compositions collectively suggest that diagenetic redox reactions take place during the abiotic decay of biomass, and that they involve Fe, sulphate, and organic matter, similarly to the pattern-forming experiments. It is concluded that chemically oscillating reactions are at least partly responsible for the formation of diagenetic siliceous spheroids and concretionary carbonate, which can relate to various other persistent problems in Earth and planetary sciences

Spin-forbidden carbon–carbon bond formation in vibrationally excited α-CO

Fourier transform infrared spectroscopy of laser-irradiated cryogenic crystals shows that vibrational excitation of CO leads to the production of equal amounts of CO2 and C3O2. The reaction mechanism is explored using electronic structure calculations, demonstrating that the lowest-energy pathway involves a spin-forbidden reaction of (CO)2 yielding C(3P) + CO2. C(3P) then undergoes barrierless recombination with two other CO molecules forming C3O2. Calculated intersystem crossing rates support the spin-forbidden mechanism, showing subpicosecond spin-flipping time scales for a (CO)2 geometry that is energetically consistent with states accessed through vibrational energy pooling. This spin-flip occurs with an estimated ∼4% efficiency; on the singlet surface, (CO)2 reconverts back to CO monomers, releasing heat which induces CO desorption. The discovery that vibrational excitation of condensed-phase CO leads to spin-forbidden C−C bond formation may be important to the development of accurate models of interstellar chemistry