Snow drop

Mercuiy in the Arctic cycles with the seasons between the atmosphere and snow on the ground. In the spring, as the sun reappears after the winter darkness, mercury levels in the troposphere decline for about 3 months. At the same time, the level of mercury in the snow increases 100-fold, both as methylmercury and as inorganic compounds of mercury. Later in the year, as the snow melts, the levels in the snow drop and mercury reappears in the troposphere. The elemental mercury in the atmosphere is converted to particulates or reactive species, parallelling a decrease in atmospheric ozone, and is then deposited in the snow. Later in the summer, the mercury levels in the atmosphere increase, probably due to temperature- or sunlight-induced emission of volatile mercury species from the surface. 

Broad, swift rivers drain mountains that receive large amounts of rain and snow. Dropping from the uplands, water rapidly accumulates kinetic energy (kinetic energy is the energy in a moving object). Hydroelectric... 

The alkaloid (—)-galanthamine, isolated from Caucasian snow-drop Galanthus woronowii) and other plant sources, is a competitive and reversible acetylcholinesterase inhibitor and an allosteric modulator of the neural nicotine receptors for acetylcholine. Galanthamine hydrobromide (commercially available as Razadyne) finds application in the treatment of symptoms of Alzheimer s disease [101]. Since the isolation of galanthamine (256) from natural sources is quite expensive, several total syntheses have been developed to date. The synthetic strategy to galanthamine (256) developed by Cho et al. [102] includes a domino Stille/Diels-Alder reaction as the key step (Scheme 14.39). 

Snow drop (GNA) Galanthus nivalis (snow drop) bulbs Amaryllidaceae Mannose a Man al,6(Man al,3)Man a-O-Methyl 28... 

Skis, both for people and for aircraft, used to be made of waxed wood. Down to about -10° C, the friction of waxed wood on snow is very low - [jl is about 0.02 - and if this were not so, planes equipped with skis could not take off from packed-snow runways, and the winter tourist traffic to Switzerland would drop sharply. Below -10° C, bad things start to happen (Fig. 26.6) (jl rises sharply to about 0.4. Polar explorers have observed this repeatedly. Wright, a member of the 1911-13 Scott expedition, writes Below 0°F (-18°C) the friction (on the sledge runners) seemed to increase progressively as the temperature fell it caused the expedition considerable hardship. What determines the friction of skis on snow ... 

A pronounced seasonal variation is observed in the coarse and fine fractions of both mass and soils, as illustrated in Figures 3 and 4. Shown are the mean values for each time period for the northern and southern halves of the network. One significant trend is the sharp decrease in coarse and fine soil and coarse mass during the winter months. The duration of this minimum is, however, different for the fine soil the fine soil drops sharply in mid-October, while the coarse soil does not drop until January. The coarse soil concentration Increases during mid-December, yet there is no corresponding fine soil increase. Also, the minimum for fine soil is more pronounced in the north than in the south, perhaps due to increased snow cover at the northern sites. Finally, these plots show the strong correlation between coarse soil and coarse mass and the considerably weaker correlation between fine soil and fine mass. It is obvious that most of the winter episodes of fine mass are not associated with fine soil. 

Diacetylaminophenol, C10HJ4NO3, may be considered as the parent compd of its tetranitro deriv but is not used to prepare it X-Tetranitrodiacetylcminopbenol, (02N)4-< (OH).N(OC.CH3)2 raw 373=56, N 18.85% col short ndls (from benz or peer ech), mp 147 47.5 was obtd when benzene-free pent an itro aniline was boiled with acetic anhydride two drops of H2SO 4, followed by cooling, removing the excess anhydride, and mixing with snow (Refs 1 2)... 

Fuse ca 100 g of pure resorcin in a porcelain casserole and immediately pour on a Pyrex glass plate. Cool and grind the cake in a mortar to pass a US Standard No 6 mesh screen. Pour 400 g of 98% nitric acid into a pint size Dewar jar and add, In small portions, while mechanically stirring, snow of carbon dioxide, until the temperature drops to -20°C. Add, in small portions and with... 

It has a strong attraction for water, and becomes hot when mixed with it. Acid of medium strength, mixed with snow, causes it to liquefy instantly, producing intense cold. Nitrio acid acts violently npon tin or iron filings, especially if they be previously moistened with a fow drops of water this aeid is, indeed, constantly employed by the chemist as an oxidising agent. In order to produce a rapid oxidation of the metals, It is host to dilute the acid until it has a specific gravity between IVd and l S5. 

In cold climates, especially when temperatures are below freezing, a water curtain may suffer operating problems when ice forms at the spray nozzles or the water drops produce snow. Either of these occurrences could result in a significant reduction in the effectiveness of a water curtain. 

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