In organic chemistry and biochemistry, a substituent is an atom or group of atoms which replaces one or more hydrogen atoms on the parent chain of a hydrocarbon, becoming a moiety of the resultant new molecule. The terms substituent and functional group, as well as other ones are used interchangeably to describe branches from a parent structure, though certain distinctions are made in the context of polymer chemistry. In polymers, side chains extend from a backbone structure. In proteins, side chains are attached to the alpha carbon atoms of the amino acid backbone; the suffix -yl is used when naming organic compounds that contain a single bond replacing one hydrogen. In addition, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent attaches to when such information is needed to distinguish between isomers; the polar effect exerted by a substituent is a combination of the inductive effect and the mesomeric effect. Additional steric effects result from the volume occupied by a substituent.
The phrases most-substituted and least-substituted are used to describe molecules and predict their products. In this terminology, methane is used as a reference of comparison. Using methane as a reference, for each hydrogen atom, replaced or "substituted" by something else, the molecule can be said to be more substituted. For example: Markovnikov's rule predicts that the hydrogen adds to the carbon of the alkene functional group that has the greater number of hydrogen atoms. Zaitsev's rule predicts that the major reaction product is the alkene with the more substituted double bond; the suffix -yl is used in organic chemistry to form names of radicals, either separate species or chemically bonded parts of molecules. It can be traced back to the old name of methanol, "methylene", which became shortened to "methyl" in compound names, from which -yl was extracted. Several reforms of chemical nomenclature generalized the use of the suffix to other organic substituents; the use of the suffix is determined by the number of hydrogen atoms that the substituent replaces on a parent compound.
According to the 1993 IUPAC recommendations: - yl means. - ylidene means that two hydrogens are replaced by a double bond between substituent. - ylidyne means that three hydrogens are replaced by a triple bond between substituent. The suffix -ylidine is encountered sporadically, appears to be a variant spelling of "-ylidene". For multiple bonds of the same type, which link the substituent to the parent group, the prefixes di-, tri-, tetra-, etc. are used: -diyl, -triyl, -tetrayl, -diylidene. For multiple bonds of different types, multiple suffixes are added: -ylylidene, -ylylidyne, -diylylidene; the parent compound name can be altered in two ways: For many common compounds the substituent is linked at one end and not numbered in the name. The IUPAC 2013 Rules however do require an explicit locant for most substituents in a preferred IUPAC name; the substituent name is modified by stripping - adding the appropriate suffix. This is "recommended only for saturated acyclic and monocyclic hydrocarbon substituent groups and for the mononuclear parent hydrides of silicon, tin and boron".
Thus, if there is a carboxylic acid called "X-ic acid", an alcohol ending "X-anol", or an alkane called "X-ane" "X-yl" denotes the same carbon chain lacking these groups but modified by attachment to some other parent molecule. The more general method omits only the terminal "e" of the substituent name, but requires explicit numbering of each yl prefix at position 1. Pentan-1-yl is an example of a name by this method, is synonymous with pentyl from the previous guideline. Note that some popular terms such as "vinyl" represent only a portion of the full chemical name. According to the above rules, a carbon atom in a molecule, considered as a substituent, has the following names depending on the number of hydrogens bound to it, the type of bonds formed with the remainder of the molecule: In a chemical structural formula, an organic substituent such as methyl, ethyl, or aryl can be written as R It is a generic placeholder, the R derived from radical or rest, which may replace any portion of the formula as the author finds convenient.
The first to use this symbol was Charles Frédéric Gerhardt in 1844. The symbol X is used to denote electronegative substituents such as the halides. One cheminformatics study identified 849,574 unique substituents up to 12 non-hydrogen atoms large and containing only carbon, nitrogen, sulfur, phosphorus and the halogens in a set of 3,043,941 molecules. Fifty substituents can be considered common as they are found in more than 1% of this set, 438 are found in more than 0.1%. 64% of the substituents are found in only one molecule. The top 5 most common are the methyl, chlorine and hydroxyl substituents; the total number of organic substituents in organic chemistry is estimated at 3.1 million, creating a total of 6.7×1023 molecules. An
The term Vaginitis emphysematosa is related to Women's Reproductive Health and coined by Zweifel in 1877. The cases of Vaginitis emphysematosa are rare; the most important thing is that women never consult with the doctors for Vaginitis emphysematosa but when they visit a doctor for some other reproductive health issue, they diagnose with the Vaginitis emphysematosa fortunately. Vaginitis emphysematosa is not common and Gynaecologists know about it; this is characterised by gas-filled cysts in the mucosa of the vagina. Vaginitis emphysematosa is a self limited cystic disorder of the vagina, it is a rare condition and has not much specific features to arouse clinical suspicion. The term"Vaginitis emphysematosa" has'vaginitis' in it but it has been observed that inflammation is mild and absent; this is characterised by gas-filled cysts in the vaginal wall and does not imply life-threatening infection. Vaginitis emphysematosa occurs in pregnant women, but there are some cases of non-pregnant women too.
It is a benign vaginal cyst identified in 173 cases. Women that have been affected were 42 to 65 years old; the cysts appear grouped but defined from one another and can be as large as 2 cm. Symptoms included: vaginal discharge, sensation of pressure, appearance of nodules, sometimes a "popping sound"; the cause is unknown. Histological examination showed the cysts contained pink hyaline-like material, foreign body-type giant cells in the cyst's wall, with chronic inflammatory cell fluid; the gas-filled cysts are identified with CT imaging. The gas contained in the cysts has been analysed and consists of nitrogen, argon, carbon dioxide, sulphur dioxide. Treatment may not be required and no complications follow the resolution of the cysts, it may be associated with trichomonas, or Haemophilus vaginalis infection. Vaginitis emphysematous is characterized by gas-filled cysts in the vaginal wall. Vaginal cysts Vaginal tumours Female reproductive system Vaginitis Female reproductive system#Vulva
Koyama Fukusei Hospital is the oldest leprosy hospital in Japan. It was established by the Roman Catholic priest Germain Léger Testevuide of the Paris Foreign Missions Society in 1889, for treating leprosy in Japan and is thereby the oldest lepers' home in Japan; as of 2009, at the time of its closure as a leprosy hospital, there were 8 ex-leprosy residents. This hospital is now open to a hospice for the terminally ill. For pronunciation, "Kohyama Fukusei Hospital" and "Kōyama Fukusei Hospital" are more descriptive. But, "Koyama Fukusei Hospital" is considered to be a reliable English spelling. 1883:Father Germain Léger Testevuide started to visit 5-6 leprosy patients living in a watermill. 1886:Father made them to live in a house. 1888:Father obtained land for a hospital. 1889:May 16, The opening of a hospital was admitted. May 22, the opening day. 1891:Father became ill and died in Hong Kong. Father Francois Paulin Vigroux assumed the post of the director. 1893:Father Lucien Joseph Jean Augustin Bertrand became the third director.
The number of in-patients was 93. 1918:Father Drouart de Lézey assumed the post of the fifth director. 1923:Yae Ibuka became the first qualified nurse of this hospital. 1930:Father Soichi Iwashita became the 6th director. 1952:A clinic was opened for citizens. 1961:Chief nurse Yae Ibuka received the Florence Nightingale Medal. 1989:100th year anniversary of this hospital. 2006:The oldest building was designated as a Registered Tangible Cultural Properties of Japan since 2011. 2009:120th year anniversary of this hospital. This building had been used until 2002 as the main building of the hospital, it houses various memorial items such as chronological tables, photographs of directors, items of patients and items concerning the Imperial Family, items of the 6th director Father Sohichi Iwashita and the first chief nurse Yae Ibuka. In 1919, there was a meeting of directors of sanatoriums and the segregation into an island was discussed. Father Lézey stated "The treatment of patients on Molokai was bad leading to riots.
The situation improved by Father Damien. Leprosy patients were to be sympathized, they do not fear anything. How do you govern them? In my sanatorium, there are 72 patients, they are brothers. I am their father. There are no quarrels; this is because of our religion. I am against the segregation into an island. On the sex segregation. "As Hannah Riddell said, I am in favor of her opinion. It is hard to prohibit marriage, but for the nation where leprosy patients are on the increase, they should not marry." Father Iwashita met Hannah Riddell in 1931 and wrote the following comments concerning her: "I do not know how Riddell herself thinks, but observing her life story, I must admit a great mission has been achieved, regardless of whether she was aware or not. God awakened the consciousness of people of Japan concerning leprosy problems. ""