A dye is a coloured substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments; the dye is applied in an aqueous solution, may require a mordant to improve the fastness of the dye on the fiber. Both dyes and pigments are colored. Dyes are soluble in water whereas pigments are insoluble; some dyes can be rendered insoluble with the addition of salt to produce a lake pigment. The majority of natural dyes are derived from plant sources: roots, bark, wood and lichens. Most dyes are synthetic, i.e. are man-made from petrochemicals. Other than pigmentation, they have a range of applications including organic dye lasers, optical media and camera sensors. Textile dyeing dates back to the Neolithic period. Throughout history, people have dyed their textiles using common, locally available materials. Scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes Tyrian purple and crimson kermes were prized luxury items in the ancient and medieval world.
Plant-based dyes such as woad, indigo and madder were important trade goods in the economies of Asia and Europe. Across Asia and Africa, patterned fabrics were produced using resist dyeing techniques to control the absorption of color in piece-dyed cloth. Dyes from the New World such as cochineal and logwood were brought to Europe by the Spanish treasure fleets, the dyestuffs of Europe were carried by colonists to America. Dyed flax fibers have been found in the Republic of Georgia in a prehistoric cave dated to 36,000 BP. Archaeological evidence shows that in India and Phoenicia, dyeing has been carried out for over 5,000 years. Early dyes were obtained from animal, vegetable or mineral sources, with no to little processing. By far the greatest source of dyes has been from the plant kingdom, notably roots, bark and wood, only few of which are used on a commercial scale; the first synthetic dye, was discovered serendipitously by William Henry Perkin in 1856. The discovery of mauveine started a surge in organic chemistry in general.
Other aniline dyes followed, such as fuchsine and induline. Many thousands of synthetic dyes have since been prepared; the discovery of mauve led to developments within immunology and chemotherapy. In 1891 Paul Ehrlich discovered that certain organisms took up certain dyes selectively, he reasoned that a sufficiently large dose could be injected to kill pathogenic microorganisms, if the dye did not affect other cells. Erlich went on to use a compound to target syphillis, the first time a chemical was used in order to selectively kill bacteria in the body, he used methylene blue to target the plasmodium responsible for malaria; the colour of a dye is dependent upon the ability of the substance to absorb light within the visible region of the electromagnetic spectrum. An earlier theory known as Witt theory stated that a coloured dye had two components, a chromophore which imparts colour by absorbing light in the visible region and an auxochrome which serves to deepen the colour; this theory has been superseded by modern electronic structure theory which states that the colour in dyes is due to excitation of valence π-electrons by visible light.
Dyes are classified according to their chemical properties. Acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool and modified acrylic fibers using neutral to acid dye baths. Attachment to the fiber is attributed, at least to salt formation between anionic groups in the dyes and cationic groups in the fiber. Acid dyes are not substantive to cellulosic fibers. Most synthetic food colors fall in this category. Examples of acid dye are Acid red 88, etc.. Basic dyes are water-soluble cationic dyes that are applied to acrylic fibers, but find some use for wool and silk. Acetic acid is added to the dye bath to help the uptake of the dye onto the fiber. Basic dyes are used in the coloration of paper. Direct or substantive dyeing is carried out in a neutral or alkaline dye bath, at or near boiling point, with the addition of either sodium chloride or sodium sulfate or sodium carbonate. Direct dyes are used on cotton, leather, wool and nylon, they are used as pH indicators and as biological stains.
Mordant dyes require a mordant, which improves the fastness of the dye against water and perspiration. The choice of mordant is important as different mordants can change the final color significantly. Most natural dyes are mordant dyes and there is therefore a large literature base describing dyeing techniques; the most important mordant dyes are chrome dyes, used for wool. The mordant potassium dichromate is applied as an after-treatment, it is important to note that many mordants those in the heavy metal category, can be hazardous to health and extreme care must be taken in using them. Vat dyes are insoluble in water and incapable of dyeing fibres directly. However, reduction in alkaline liquor produces the water-soluble alkali metal salt of the dye; this form is colorless, in which case it is referred to as a Leuco dye, has an affinity for the textile fibre. Subsequent oxidation reforms the original insoluble dye; the color of denim is due to the original vat dye. Reactive dyes u
Country Boy is the 28th studio album released by Irish singer Daniel O'Donnell in 2008. The album consists of covers of popular country songs, including duets with Charley Pride and Loretta Lynn. I'm Going to Be a Country Boy Again – 2:16 If I Said You Had a Beautiful Body Would You Hold It Against Me – 3:44 Lucille – 3:30 Back Home Again – 4:21 Me and Bobby McGee – 4:16 King of the Road – 2:47 Little Ole Wine Drinker Me – 3:10 Release Me – 3:20 From Here To There To You – 2:08 Detroit City – 3:12 I Wanna Be Free – 2:20 Mother's Birthday Song – 3:37 Crystal Chandeliers - 2:48 Seven Spanish Angels - 3:54 Ring of Fire - 2:41 He Stopped Loving Her Today - 3:23 Okie From Muskogee - 2:58 I'm Just Lucky I Guess - 2:24 Could I Have This Dance For The Rest Of My Life - 3:39 Oh Lonesome Me - 2:38 Daniel O'Donnell's website
Rudi Wetzel was a German political activist who became an East German journalist and newspaper editor after the Second World War. Rudolf "Rudi" Wetzel was born in Rechenberg, a small town in the mining region of Saxony on the frontier with what was, at that time, the Austrian province of Bohemia, his father worked as a furniture painter. After leaving school he attended the Construction Academy in Dresden before embarking, in 1929, on the study of Pedagogy at the Dresden Technical University, it was in 1929 that he joined the Social Democratic Party. In 1931 he switched to the Communist Party. During the next couple of years he served as a party officer as chair of the Communist Students's Association in Dresden, it was during this time that he met the Hungarian Communist activist, Inke Rosza, who became his partner - also at some stage his wife. Early in 1933 the Nazis took power and lost no time in transforming Germany into a one-party dictatorship; the Reichstag fire at the end of February 1933 was blamed, with implausible haste, on "communists" and indeed people with records as communist activists were among those most assiduously targeted by the authorities.
Wetzel continued with his political activity after it became illegal and was first taken into "protective custody" in 1933, which put an end to his student career. In 1934 he was sentenced to a two-year prison term for "preparing to commit high treason"; when the two years had been served he was transferred to the Sachsenburg concentration camp. He was released in 1937, shortly after. Travelling via Paris and London he made his way to Hull in eastern England where he trained and worked as a welder. In 1938 he moved on to Gothenburg and Jönköping in Sweden, where as a qualified welder he had no difficulty in obtaining work, he joined the Swedish Metal Workers' Union. After his emigration to Sweden the Nazi police departments back in Germany identified Wetzel as a public enemy, they incorrectly believed. Early in 1940 the Security Services in Berlin added his name to the "Sonderfahndungsliste G. B.", a list of 2,820 individuals who would, in the event of a successful German invasion and occupation of Britain, be sought out by commando task forces and arrested as a priority.
In August 1939 Wetzel was the author of the so-called "Gothenburg Resolution", critical of the non-aggression pact concluded between Germany and the Soviet Union that month. This opened Wetzel up to criticism from the leadership of the exiled Communist Party leadership based in Moscow. Wetzel's "Gothenburg Resolution" insisted that, despite the non-aggression pact, it was still Hitler and his power structure that must be seen as the true enemies of the German working class, rather than the old imperialist powers of Britain and France that were the implicit targets of understandings between Hitler and Stalin. Walter Ulbricht prominent among the exiled German communists in Moscow, issued instructions that German communists in Sweden should "isolate" Wetzel. If subsequent events may have vindicated Wetzel's judgements, incurring the suspicions of the man who became the first leader of the German Democratic Republic is unlikely to have boosted his career prospects in Germany's Soviet occupation zone after 1945.
In 1942 Wetzel relocated to Stockholm. The 1941 German invasion of the Soviet Union had led to a stark political reconfiguration affecting the various strands of the exiled German communist party. Wetzel's "Gothenburg Resolution" had become redundant, by 1943 he was again engaged in party work. Around this time he and Inke separated, he became editorial secretary of "Politische Information", a German language party newspaper produced in the Swedish capital. He produced a significant number of articles for it using one of a succession of pseudonyms, including "Ber Wernau", "Karl Scharf" and "Max Richter", his activities came to the attention of the authorities in Germany, he was formally deprived of his German nationality on 21 October 1944. War ended again in May 1945; the large central area of Germany surrounding Berlin, including Wetzel's Saxon homeland, was now administered as the Soviet occupation zone. He returned, now moving directly to Berlin, in January 1946, accompanied by his new Swedish wife, Inge: the marriage would prove short-lived.
He was appointed to a senior management position with the press and broadcasting department of the Central Committee of the newly formed Socialist Unity Party. In 1947 he became head of the foreign press section, with the title "Second Deputy Head of the Agitation Department"; the contentious launch in April 1946 of the SED had been part of a nation building exercise planned with Moscow support by a team of leading exiled German communists during the war years and implemented during the 1940s. In October 1949 the Soviet occupation zone was relaunched as the Soviet sponsored German Democratic Republic, a new kind of one-party dictatorship. Wetzel was sent to study at the "Karl Marx" Party Academy. Between 1950 and 1953 he served as managing editor of "Neuer Weg", a journal produced for SED party officials. At the same time he was a member of the presidium of the "International Journalists' Organisation". During the early part of 1953 he was editor in chief at the news-magazine "Friedenspost". After a few months he