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Robert Franz

Robert Franz (28 June 1815 – 24 October 1892) was a German composer, mainly of lieder.

Biography

He was born Robert Franz Julius Knauth in Halle, Germany, the son of Christoph Franz Knauth. In 1847, Christoph Knauth adopted his middle name Franz as his new surname, and his son followed suit.

He suffered in early life from the hostility of his parents to a musical career. He was twenty years old when his father's animosity was conquered and he was allowed to live in Dessau to study organ playing under Friedrich Schneider. The two years of study under that famous teacher were advantageous chiefly in making him uncommonly intimate with the works of Bach and Händel, his knowledge of which be shown in his editions of the former's St Matthew Passion, Magnificat and ten cantatas, and the latter's Messiah and L'Allegro, although some of these editions have long been controversial among musicians.

In 1843 he published his first book of songs, which was followed by some fifty more books, containing in all about 250 songs. In his native Halle he filled various public offices, including those of city organist as well as conductor of the Singakademie and the Symphony. He also served as royal music-director and music master at the university. The first book of songs was warmly praised by Liszt and Schumann, and the latter wrote a lengthy review of it in the Neue Zeitschrift für Musik and later published it separately as well.

Vitamin C

Vitamin C or L-ascorbic acid, or simply ascorbate (the anion of ascorbic acid), is an essential nutrient for humans and certain other animal species. Vitamin C describes several vitamers that have vitamin C activity in animals, including ascorbic acid and its salts, and some oxidized forms of the molecule like dehydroascorbic acid. Ascorbate and ascorbic acid are both naturally present in the body when either of these is introduced into cells, since the forms interconvert according to pH.

Vitamin C is a cofactor in at least eight enzymatic reactions, including several collagen synthesis reactions that, when dysfunctional, cause the most severe symptoms of scurvy. In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries. Ascorbate may also act as an antioxidant against oxidative stress.

Ascorbate (the anion of ascorbic acid) is required for a range of essential metabolic reactions in all animals and plants. It is made internally by almost all organisms; the main exceptions are most bats, all guinea pigs, capybaras, and the Haplorrhini (one of the two major primate suborders, consisting of tarsiers, monkeys, and humans and other apes). Ascorbate is also not synthesized by some species of birds and fish. All species that do not synthesize ascorbate require it in the diet. Deficiency in this vitamin causes the disease scurvy in humans.

Vitamin D

Vitamin D refers to a group of fat-soluble secosteroids responsible for enhancing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D₃ (also known as cholecalciferol) and vitamin D₂ (ergocalciferol). Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Very few foods contain vitamin D; synthesis of vitamin D (specifically cholecalciferol) in the skin is the major natural source of the vitamin. Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis from sunlight is biologically inactive; activation requires enzymatic conversion (hydroxylation) in the liver and kidney. Evidence indicates the synthesis of vitamin D from sun exposure is regulated by a negative feedback loop that prevents toxicity, but because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine (US), for the amount of sun exposure required to meet vitamin D requirements. Accordingly, the Dietary Reference Intake for vitamin D assumes no synthesis occurs and all of a person's vitamin D is from food intake, although that will rarely occur in practice. As vitamin D is synthesized in adequate amounts by most mammals exposed to sunlight, it is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations. Vitamin D has a significant role in calcium homeostasis and metabolism. Its discovery was due to effort to find the dietary substance lacking in rickets (the childhood form of osteomalacia).