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Hexachlorobenzene
Hexachlorobenzene, or perchlorobenzene, is an organochloride with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt. It has been banned globally under the Stockholm Convention on Persistent Organic Pollutants. Physical and chemical properties Hexachlorobenzene is a stable, white, crystalline chlorinated hydrocarbon. It is sparingly soluble in organic solvents such as benzene, diethyl ether and alcohol, but practically insoluble in water with no reaction. It reacts violently above 65 °C with dimethyl formamide and has a flash point of 468 °F. It is stable under normal temperatures and pressures. It is combustible but it does not ignite readily. When heated to decomposition, hexachlorobenzene emits highly toxic fumes of hydrochloric acid, other chlorinated compounds (such as phosgene), carbon monoxide, and carbon dioxide. Synthesis Hexachlorobenzene has been made on a laboratory scale since th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexafluorobenzene
Hexafluorobenzene, HFB, , or perfluorobenzene is an organic, aromatic compound. In this derivative of benzene all hydrogen atoms have been replaced by fluorine atoms. The technical uses of the compound are limited, although it is recommended as a solvent in a number of photochemical reactions. In the laboratory hexafluorobenzene is used as standard in fluorine-19 NMR spectroscopy, solvent and standard in carbon-13 NMR, solvent in proton NMR, solvent when studying some parts in the infrared and solvent in ultraviolet–visible spectroscopy, as hexafluorobenzene itself hardly shows any absorbance in the UV region. Geometry of the aromatic ring Hexafluorobenzene stands somewhat aside in the perhalogenbenzenes. When counting for bond angles and distances it is possible to calculate the distance between two ortho fluorine atoms. Also the non bonding radius of the halogens is known. The following table presents the results: The conclusion of the table is hexafluorobenzene is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stockholm Convention On Persistent Organic Pollutants
Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs). History In 1995, the Governing Council of the United Nations Environment Programme (UNEP) called for global action to be taken on POPs, which it defined as "chemical substances that persist in the environment, bio-accumulate through the food web, and pose a risk of causing adverse effects to human health and the environment". Following this, the Intergovernmental Forum on Chemical Safety (IFCS) and the International Programme on Chemical Safety (IPCS) prepared an assessment of the 12 worst offenders, known as the ''dirty dozen''. The INC met five times between June 1998 and December 2000 to elaborate the convention, and delegates adopted the Stockholm Convention on POPs at the Conference of the Plenipotentiaries co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hydroxyl group). Ethanol is a Volatility (chemistry), volatile, Combustibility and flammability, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. It is a psychoactive recreational drug, the active ingredient in alcoholic drinks. Ethanol is naturally produced by the fermentation process of Carbohydrate, sugars by yeasts or via Petrochemistry, petrochemical processes such as ethylene hydration. It has medical applications as an antiseptic and disinfectant. It is used as a chemical solvent and in the Chemical synthesis, synthesis of organic compounds, and as a Alcohol fuel, fuel source. Ethanol also can be dehydrated to make ethylene, an important chemical feedstock. As of 2006, world produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agriculture
Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities. The history of agriculture began thousands of years ago. After gathering wild grains beginning at least 105,000 years ago, nascent farmers began to plant them around 11,500 years ago. Sheep, goats, pigs and cattle were domesticated over 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. Industrial agriculture based on large-scale monoculture in the twentieth century came to dominate agricultural output, though about 2 billion people still depended on subsistence agriculture. The major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials (such as rubber). Food classes include cereals (grains), vegetables, fruits, cooking oils, meat, milk, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosensitivity
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity. The photosensitive ganglion cells in the mammalian eye are a separate class of light-detecting cells from the photoreceptor cells that function in vision. Skin reactions Human medicine Sensitivity of the skin to a light source can take various forms. People with particular skin types are more sensitive to sunburn. Particular medications make the skin more sensitive to sunlight; these include most of the tetracycline antibiotics, heart drugs amiodarone, and sulfonamides. Some dietary supplements, such as St. John's Wort, include photosensitivity as a possible side effect. Particular conditions lead to increased light sensitivity. Patients with systemic lupus erythematosus experience skin symptoms after sunlight exposure; some types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ulcer (dermatology)
An ulcer is a sore on the skin or a mucous membrane, accompanied by the disintegration of tissue. Ulcers can result in complete loss of the epidermis and often portions of the dermis and even subcutaneous fat. Ulcers are most common on the skin of the lower extremities and in the gastrointestinal tract. An ulcer that appears on the skin is often visible as an inflamed tissue with an area of reddened skin. A skin ulcer is often visible in the event of exposure to heat or cold, irritation, or a problem with blood circulation. They can also be caused due to a lack of mobility, which causes prolonged pressure on the tissues. This stress in the blood circulation is transformed to a skin ulcer, commonly known as bedsores or decubitus ulcers. Ulcers often become infected, and pus forms. Signs and symptoms Skin ulcers appear as open craters, often round, with layers of skin that have eroded. The skin around the ulcer may be red, swollen, and tender. Patients may feel pain on the skin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porphyria Cutanea Tarda
Porphyria cutanea tarda is the most common subtype of porphyria. The disease is named because it is a porphyria that often presents with skin manifestations later in life. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs. It is a component of hemoglobin, the molecule that carries oxygen in the blood. Hepatoerythropoietic porphyria has been described as a homozygous form of porphyria cutanea tarda, although it can also be caused if two different mutations occur at the same locus. Symptoms and signs Porphyria cutanea tarda (PCT) is recognized as the most prevalent subtype of porphyritic diseases. PCT is characterized by onycholysis and blistering of the skin in areas that receive higher levels of exposure to sunlight. The primary cause is a deficiency of uroporphyrinogen decarboxylase (UROD), a cytosolic enzyme that is a step in the enzymatic pathway that leads to the synthes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroid Cancer
Thyroid cancer is cancer that develops from the tissues of the thyroid gland. It is a disease in which cells grow abnormally and have the potential to spread to other parts of the body. Symptoms can include swelling or a lump in the neck. Cancer can also occur in the thyroid after spread from other locations, in which case it is not classified as thyroid cancer. Risk factors include radiation exposure at a young age, having an enlarged thyroid, and family history. The four main types are papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, and anaplastic thyroid cancer. Diagnosis is often based on ultrasound and fine needle aspiration. Screening people without symptoms and at normal risk for the disease is not recommended as of 2017. Treatment options may include surgery, radiation therapy including radioactive iodine, chemotherapy, thyroid hormone, targeted therapy, and watchful waiting. Surgery may involve removing part or all of the thyroid. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kidney Cancer
Kidney cancer, also known as renal cancer, is a group of cancers that starts in the kidney. Symptoms may include blood in the urine, lump in the abdomen, or back pain. Fever, weight loss, and tiredness may also occur. Complications can include spread to the lungs or brain. The main types of kidney cancer are renal cell cancer (RCC), transitional cell cancer (TCC), and Wilms tumor. RCC makes up approximately 80% of kidney cancers, and TCC accounts for most of the rest. Risk factors for RCC and TCC include smoking, certain pain medications, previous bladder cancer, being overweight, high blood pressure, certain chemicals, and a family history. Risk factors for Wilms tumor include a family history and certain genetic disorders such as WAGR syndrome. Diagnosis maybe suspected based on symptoms, urine testing, and medical imaging. It is confirmed by tissue biopsy. Treatment may include surgery, radiation therapy, chemotherapy, immunotherapy, and targeted therapy. Kidney cancer newly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver Cancer
Liver cancer (also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy) is cancer that starts in the liver. Liver cancer can be primary (starts in liver) or secondary (meaning cancer which has spread from elsewhere to the liver, known as liver metastasis). Liver metastasis is more common than that which starts in the liver. Liver cancer is increasing globally. Primary liver cancer is globally the sixth-most frequent cancer and the fourth-leading cause of death from cancer. In 2018, it occurred in 841,000 people and resulted in 782,000 deaths globally. Higher rates of liver cancer occur where hepatitis B and C are common, including Asia and sub-Saharan Africa. Males are more often affected with hepatocellular carcinoma (HCC) than females. Diagnosis is most frequent among those 55 to 65 years old. The leading cause of liver cancer is cirrhosis due to hepatitis B, hepatitis C or alcohol. Other causes include aflatoxin, non-alcoholic fatty liver disease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Agency For Research On Cancer
The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and coordinate research into the causes of cancer. It also collects and publishes surveillance data regarding the occurrence of cancer worldwide. Its IARC monographs programme identifies carcinogenic hazards and evaluates environmental causes of cancer in humans. IARC has its own governing council, and in 1965 the first members were the Federal Republic of Germany, France, Italy, the United Kingdom, and the United States of America. Today, IARC's membership has grown to 27 countries. History In late February 1963, after he experienced his spouse suffering and dying of cancer, journalist and peace activist Yves Poggioli sent a letter to Emmanuel d'Astier de la Vignerie relating his story, and urging support for the creation of an intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
