96.1 Star FM

96.1 Star FM (ACMA callsign: 5SEF) is an Australian commercial radio station based in Mount Gambier, South Australia, owned by Southern Cross Austereo. It commenced broadcasting on May 16, 1998. Currently, the only local program broadcast on the station is the Jess and Ryan breakfast show from 6am to 9am Monday to Friday - all other programming is broadcast from Albury or Gold Coast.

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Selenium hexafluoride

Selenium hexafluoride is the inorganic compound with the formula SeF₆. It is a colourless gas described as having a "repulsive" odor. It is not widely encountered and has no commercial applications.

Structure, preparation, and reactions

Like many compounds of selenium, SeF₆ is hypervalent. The compound has octahedral molecular geometry with Se-F bond length 168.8 pm.

SeF₆ can be prepared from the elements or by the reaction of bromine trifluoride (BrF₃) with selenium dioxide. The crude product is purified by sublimation.

The relative reactivity of the hexafluorides of S, Se, and Te follows the order TeF₆ > SeF₆ > SF₆, the latter being completely inert toward hydrolysis until high temperatures. SeF₆ also resists hydrolysis. The gas can be passed through 10% NaOH or KOH without change, but reacts with gaseous ammonia at 200 °C.

Safety

Although selenium hexafluoride is quite inert and slow to hydrolyze, it is toxic even at low concentrations, especially by longer exposure. In the U.S., OSHA and ACGIH standards for selenium hexafluoride exposure is an upper limit of 0.05 ppm in air averaged over an eight-hour work shift. Additionally, selenium hexafluoride is designated as IDLH chemical with a maximum allowed exposure limit of 2 ppm.

Selenium tetrafluoride

Selenium tetrafluoride (SeF₄) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

Synthesis

The first reported synthesis of selenium tetrafluoride was by Paul Lebeau in 1907, who treated selenium with fluorine:

A synthesis involving more easily handled reagents entails the fluorination of selenium dioxide with sulfur tetrafluoride:

An intermediate in this reaction is seleninyl fluoride (SeOF₂).

Other methods of preparation include fluorinating elemental selenium with chlorine trifluoride:

Structure and bonding

Selenium in SeF₄ has an oxidation state of +4. Its shape in the gaseous phase is similar to that of SF₄, having a see-saw shape. VSEPR theory predicts a pseudo-trigonal pyramidal disposition of the five electron pairs around the selenium atom. The axial Se-F bonds are 177 pm with an F-Se-F bond angle of 169.2°. The two other fluorine atoms are attached by shorter bonds (168 pm), with an F-Se-F bond angle of 100.6°. In solution at low concentrations this monomeric structure predominates, but at higher concentrations evidence suggests weak association between SeF₄ molecules leading to a distorted octahedral coordination around the selenium atom. In the solid the selenium center also has a distorted octahedral environment.

Firefly

The Lampyridae are a family of insects in the beetle order Coleoptera. They are winged beetles, and commonly called fireflies or lightning bugs for their conspicuous use of bioluminescence during twilight to attract mates or prey. Fireflies produce a "cold light", with no infrared or ultraviolet frequencies. This chemically produced light from the lower abdomen may be yellow, green, or pale red, with wavelengths from 510 to 670 nanometers.

About 2,000 species of fireflies are found in temperate and tropical environments. Many are in marshes or in wet, wooded areas where their larvae have abundant sources of food. Their larvae emit light and often are called "glowworms", in particular, in Eurasia. In the Americas, "glow worm" also refers to the related Phengodidae. In many species, both male and female fireflies have the ability to fly, but in some species, the females are flightless.

Biology

Fireflies tend to be brown and soft-bodied, often with the elytra, or front wings, more leathery than those of other beetles. Although the females of some species are similar in appearance to males, larviform females are found in many other firefly species. These females can often be distinguished from the larvae only because they have compound eyes. The most commonly known fireflies are nocturnal, although there are numerous species that are diurnal. Most diurnal species are not luminescent; however, some species that remain in shadowy areas may produce light.

Fireflies (Frodus album)

Fireflies is the second studio album by American post-hardcore band Frodus, released in 1995 through Level Records. The album was initially going to be a glow-in-the-dark 7" single until the band decided to instead release a full-length album because it was "just as cheap".<ref name=Frodus bandcamp>Frodus. "Fireflies!". Retrieved April 25, 2015. </ref> The album was initially released on CD format, limited to 1,100 copies.<ref name=Frodus.com>Frodus. "Frodus Discography". Retrieved April 25, 2015. </ref> The album was reissued digitally in 2006, remastered and with new artwork and an alternative track listing. The band's bandcamp page also hosts another reissue of the record, also including unique cover art and track listing.

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Personnel

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Fireflies (computer graphics)

Fireflies are rendering artifacts resulting from numerical instabilities in solving the rendering equation. They manifest themselves as anomalously-bright single pixels scattered over parts of the image.

Fireflies need to be distinguished from noise (overall graininess in the image), which can be reduced by simply increasing the number of rendering samples (amount of computation) per pixel. Fireflies tend to be harder to get rid of.

Fireflies tend to be confined to particular parts of the image, where they are caused by interactions between particular material and lighting settings that only affect certain objects in the scene.

Curing Fireflies

Sometimes fireflies can be reduced by various tweaks to renderer settings, for example clamping the maximum intermediate amplitude during pixel calculations, or disabling the calculation of caustics if these are not needed. Another option is application of a despeckle filter as part of rendering post-processing, or manually removing the fireflies with the brush or clone tool in an image editor.