Il trovatore is an opera in four acts by Giuseppe Verdi to an Italian libretto written by Salvadore Cammarano, based on the play El trovador by Antonio García Gutiérrez. It was Gutiérrez's most successful play, one which Verdi scholar Julian Budden describes as "a high flown, sprawling melodrama flamboyantly defiant of the Aristotelian unities, packed with all manner of fantastic and bizarre incident."The premiere took place at the Teatro Apollo in Rome on 19 January 1853, where it "began a victorious march throughout the operatic world," a success due to Verdi's work over the previous three years. It began with his January 1850 approach to Cammarano with the idea of Il trovatore. There followed and with interruptions, the preparation of the libretto, first by Cammarano until his death in mid-1852 and with the young librettist Leone Emanuele Bardare, which gave the composer the opportunity to propose significant revisions, which were accomplished under his direction; these revisions are seen in the expansion of the role of Leonora.

For Verdi, the three years were filled with musical activity. His personal affairs limited his professional work. In May 1851, an additional commission was offered by the Venice company after Rigoletto's success there. Another commission came from Paris while he was visiting that city from late 1851 to March 1852. Before the libretto for Il trovatore was completed, before it was scored, before it premiered, Verdi had a total of four different operatic projects in various stages of development. Today, Il Trovatore is performed and is a staple of the standard operatic repertoire. How and when Verdi acquired a copy of the Gutiérrez play is uncertain, but Budden notes that it appears that Giuseppina Strepponi, with whom Verdi had been living in Busseto since September 1849, had translated the play, as evidenced in a letter from her two weeks before the premiere urging him to "hurry up and give OUR Trovatore"; when considering setting Gutiérrez's play, Verdi turned to work with Cammarano, "the born operatic poet".

Their correspondence began as early as January 1850, well before Verdi had done anything to develop a libretto with Piave for what became Rigoletto in Venice. At this time, it was the first since Oberto that the composer was beginning to prepare an opera with a librettist but without a commission of any kind from an opera house. In his first letter to Cammarano, Verdi proposed El Trovador as the subject with "two feminine roles; the first, the gypsy, a woman of unusual character after whom I want to name the opera."With regard to the chosen librettist's strength as a poet in preparing verse for opera, Budden comments that his approach was traditional, something which began to become clear during the preparation of the libretto and which appears in the correspondence between the two men. Verdi's time and energy were spent on finishing Rigoletto, which premiered at La Fenice in Venice in March 1851. Within a matter of weeks, Verdi was expressing his frustration to a mutual friend, de Sanctis, at having no communication from Cammarano.

His letter emphasized that "the bolder he is, the happier it will make me," although it appears that Cammarano's reply contained several objections, which Verdi answered on 4 April and, in his response, he emphasized certain aspects of the plot which were important to him. These included Leonora taking the veil and the importance of the Azucena/Manrico relationship, he continued by asking whether the librettist liked the drama and emphasized that "the more unusual and bizarre the better". Verdi writes that if there were no standard forms – "cavatinas, trios, finales, etc. and if you could avoid beginning with an opening chorus...." He would be quite happy. Correspondence continued between the two men for the following two months or so, including another letter from the composer of 9 April which included three pages of suggestions, but he made concessions and expresses his happiness in what he is receiving in the way of verse. During the period to follow, in spite of his preoccupations but after he had begun to overcome them, Verdi had kept in touch with the librettist.

In a letter around the time of his intended departure for France, he wrote encouragingly to Cammarano: "I beg you with all my soul to finish this Trovatore as as you can." There arose the question of where the opera would be presented. Verdi had turned down an offer from Naples, but became concerned about the availability of his preferred Azucena, Rita Gabussi-De Bassini, she expressed an interest in the possibility of Rome. Things were put on hold for several months as Verdi became preoccupied with family matters, which included the illnesses of both his mother and father, the estrangement from his parents with communications conducted only between lawyers, the administration of his newly acquired property at Sant'Agata, where he had established his parents, but his relationship with his parents, albeit severed, as well as Strepponi's situation living with the composer in an unmarried state, continued to preoccupy him, as did the deterioration of his relationship with his father-in-law, Antonio Barezzi.

In April 1851, agreement was reached with the elder Verdis on the payment of debts mutually owed and the couple were given time to resettle, leaving Sant'Agata for Verdi and Strepponi to occupy for the next fifty years. May 1851 brought an offer for a new opera from the Venice

David Sidney Feingold was an American biochemist. Feingold was born in Chelsea, United States in 1922. In 1944 he graduated from Massachusetts Institute of Technology with a bachelor's degree in chemistry. Following his graduation, he enlisted in the United States Navy. Feingold served on an LST in the Pacific for nine months, from 1945 to 1946. From 1947 to 1949 he continued his studies in chemistry at the Chemical Institute at the University of Zurich, in Switzerland. In 1949 he moved to Israel; until 1950, he served in the scientific division of the Israeli Army as a second lieutenant. From 1950 to 1951, he worked at the Hadassah Hospital in Jerusalem. Between 1951 and 1956, Feingold was a student of biochemistry in Jerusalem. In 1956 he was awarded a Ph. D. from the Hebrew University of Jerusalem. Following receipt of his PhD he returned to the United States and served as a research assistant at the University of California from 1956 to 1960. In 1960 he moved to the University of Pittsburgh as an assistant professor in the department of biology.

In 1966 he was appointed Professor of Microbiology at the University of Pittsburgh School of Medicine. He served as an invited professor in Switzerland and Argentina, as well as at the University of Colorado, he taught until his retirement in 1993. He died in September 2019 at the age of 96. In 1957 Feingold was awarded the Israel Prize, in exact sciences, jointly with his research partner Shlomo Hestrin and their student Gad Avigad. Infection-promoting activity of levan and dextran as a function of degree of polymerization. Synthesis of sucrose and other beta-D-fructofuranosyl adolases by levansucrase. An enzymic synthesis of a sucrose analog: α-D-xylopyranosyl-β-fructofuranoside; the mechanism of polysaccharide production from sucrose. 4. Isolation and probable structures of oligosaccharides formed from sucrose by a levansucrase system. Enzymatic synthesis and reactions of a sucrose isomer α-D-galactopyransoyl β-D-fructofuranoside; the structure and properties of levan, a polymer of D-fructose produced by cultures and cell-free extracts of Aerobacter levanicum.

Uridine diphosphate N-acetylglucosamine and uridine diphosphate glucuronic acid in mung bean seedlings. Enzymatic synthesis of uridine diphosate glucuronic acid and uridine diphosphate galacturonic acid with extracts from Phaseolus aureus seedlings. Xylosyl transfer by asparagus extracts. Sugar nucleotides in the interconversion of sugars of higher plants; the 4-epimerization and decarboxylation of DUP-D-glucuronic acid by extracts of Phaseolus aureus seedings. Decarboxylation of uridine diphosphate-D-glucuronic acid by an enzyme preparation from hen oviduct. Uridine diphosphate D-xylose: acceptor xylosyltransferase of Cryptococcus laurentii. Interferon production in mice by cell wall mutants of Salmonella typhimurium. L-Rhamnulose 1-phosphate aldolase from Escherichia coli. Crystallization and cirteria of purity. Biosynthesis of uridine diphosphate-D-xylose. IV. Mechanism of action of UDP-glucuronate carboxyl-lyase. Biosynthesis of uridine diphosphate-D-xylose. V. UDP-D-glucuronate and UDP-D-galacturonate carboxy-lyase of Ampullariella digitata.

Uridine diphosphate-D-glucose dehydrogenase of beef liver. Subunit structure and sulfhydryl groups. List of Israel Prize recipients Feingold

Carl Henry Kaeppel MC BA referred to as Carl Kaeppel, was an Australian scholar of Classical languages and geography. Kaeppel was born at Nattai near Mittagong, New South Wales, a son of Herbert Kaeppel and Emily Annette Kaeppel, née Edwards, his father died. Kaeppel was educated at Sydney Grammar School of which he was captain in 1905, at Sydney University, where he graduated BA with first-class honours in Classics in 1910, having won the Salting exhibition, Cooper scholarship, Cooper travelling scholarship, which entitled him to go to Oxford, but illness prevented him from taking up the opportunity but was able to undertake a long tour of Europe, studying languages, he returned to Australia, serving as a master at Sydney Grammar School, North Sydney for some years at The Armidale School, Armidale. He enlisted with First AIF in January 1916 and in mid-March as Lieut. Kaeppel left to serve overseas with the 18th Battalion, he was mentioned in dispatches and won the Military Cross. He worked at the British Museum on early geographic texts, did a course in anthropology at London University under Professor Seligman.

Kaeppel learned eleven languages, but was no polyglot. He returned to Australia, where by 1922 he had been appointed senior classics master at Melbourne Grammar School by headmaster R. P. Franklin, a close friend but in 1931 was forced to leave on account of his heavy drinking, he moved to Sydney. Kaeppel engaged in research on Classical geography and anthropology, articles based on this work, read before the Classical Association of Victoria, were published as Off the Beaten Track in the Classics in 1936, he converted to the Roman Catholic faith in that same year, devoted the last years of his life to Catholic education, teaching at Marist Brothers' High School, St Vincent's College, Potts Point. He edited a regular page on education for The Catholic Weekly, he died in Lewisham Private Hospital, aged 59. Requiem Mass was celebrated at St Canice's Church and his remains were buried in Waverley Cemetery. Kaeppel married Muriel Beatrice Bailie on 8 January 1916, she left him while he was overseas and they were divorced in 1920.

Kaeppel was described as a lovable character and trustworthy, who loved knowledge for its own sake. He was a voracious reader, not only retained all he read but could cross-reference that information and draw inferences and reach surprising conclusions from the mass of mental data, he carried in his head the makings of a multitude of books, though he only completed one or two. Despite being unable to pronounce an "R", so that "Greek" came out "Gweek", he was a welcome conversationalist and a writer and speaker to a range of subjects on ABC radio. An habitué of the Savage and Naval and Military clubs, he was a hard drinker, generous to a fault devoid of worldly ambition and died penniless and before his time. Thanks to an anonymous benefaction, annual prizes for study in the classics, known as the Carl Kaeppel Memorial Prize, were instituted at the Marist Brothers' High School, Darlinghurst. Carl Kaeppel. A Short History of Latin Literature; the Shakespeare Head Press. Carl Kaeppel. Off the Beaten Track in the Classics.

Carl Kaeppel. Caesar, Gallic War. Book V. Shakespeare Head Press. Used by State Education Departments. Kaeppel at the Australian War Memorial