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AcneFree
Benzoyl peroxide is a chemical compound (specifically, an organic peroxide) with structural formula , often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as two benzoyl (, Bz) groups connected by a peroxide (). It is a white granular solid with a faint odour of benzaldehyde, poorly soluble in water but soluble in acetone, ethanol, and many other organic solvents. Benzoyl peroxide is an oxidizer, but it is principally used as in the production of polymers. Benzoyl peroxide is mainly used in production of plastics and for bleaching flour, hair, plastics and textiles. Synthesis, structure, and chemical reactivity The original 1858 synthesis by Liebig reacted benzoyl chloride with barium peroxide, a reaction described by the following idealized equation: : Benzoyl peroxide is usually prepared by treating hydrogen peroxide with benzoyl chloride under alkaline conditions. : As in many other peroxides, the C-O-O-C linkage has a dihedral angle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Topical Administration
A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surfaces such as the skin or mucous membranes to treat ailments via a large range of classes including creams, foams, gels, lotions, and ointments. Many topical medications are epicutaneous, meaning that they are applied directly to the skin. Topical medications may also be inhalational, such as asthma medications, or applied to the surface of tissues other than the skin, such as eye drops applied to the conjunctiva, or ear drops placed in the ear, or medications applied to the surface of a tooth. The word ''topical'' derives from Greek τοπικός ''topikos'', "of a place". Justification Topical drug delivery is a route of administering drugs via the skin to provide topical therapeutic effects. As skin is one of the largest and most superficial organs in the human body, pharmacists utilise it to deliver various drugs. This ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Justus Liebigs Ann
Justus (died on 10 November between 627 and 631) was the fourth Archbishop of Canterbury. He was sent from Italy to England by Pope Gregory the Great, on a mission to Christianize the Anglo-Saxons from their native paganism, probably arriving with the second group of missionaries despatched in 601. Justus became the first Bishop of Rochester in 604, and attended a church council in Paris in 614. Following the death of King Æthelberht of Kent in 616, Justus was forced to flee to Gaul, but was reinstated in his diocese the following year. In 624 Justus became Archbishop of Canterbury, overseeing the despatch of missionaries to Northumbria. After his death he was revered as a saint, and had a shrine in St Augustine's Abbey, Canterbury. Arrival in Britain Justus was a member of the Gregorian mission sent to England by Pope Gregory I. Almost everything known about Justus and his career is derived from the early 8th-century ''Historia ecclesiastica gentis Anglorum'' of Bede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chain-growth Polymerization
Chain-growth polymerization (American English, AE) or chain-growth polymerisation (British English, BE) is a polymerization technique where Unsaturated compound, unsaturated monomer molecules add onto the active site on a growing polymer chain one at a time. There are a limited number of these active sites at any moment during the polymerization which gives this method its key characteristics. Introduction In 1953, Paul Flory first classified polymerization as "step-growth polymerization" and "chain-growth polymerization". IUPAC recommends to further simplify "chain-growth polymerization" to "chain polymerization". It is a kind of polymerization where an active center (free radical or ion) is formed, and a plurality of monomers can be polymerized together in a short period of time to form a macromolecule having a large molecular weight. In addition to the regenerated active sites of each monomer unit, polymer growth will only occur at one (or possibly more) endpoint. Many comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical Initiator
In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical initiators are utilized in industrial processes such as polymer synthesis. Typical examples are molecules with a nitrogen-halogen bond, azo compounds, and organic and inorganic peroxides. Main types of initiation reaction *Halogens undergo homolytic fission relatively easily. Chlorine, for example, gives two chlorine radicals (Cl•) by irradiation with ultraviolet light. This process is used for chlorination of alkanes. *Azo compounds (R- N=N-R') can be the precursor of two carbon-centered radicals (R• and R'•) and nitrogen gas upon heating and/or by irradiation. For example, AIBN and ABCN yield isobutyronitrile and cyclohexanecarbonitrile radicals, respectively. : *Organic peroxides each have a peroxide bond (- O-O-), which is readi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acne Miliaris Necrotica
Acne miliaris necrotica is a rare condition consisting of follicular vesicopustules, sometimes occurring as solitary lesions that are usually very itchy.James, William; Berger, Timothy; Elston, Dirk (2005). ''Andrews' Diseases of the Skin: Clinical Dermatology''. (10th ed.). Saunders. Page 245. . The condition affects middle aged and elderly individuals. Affected areas can include the scalp, frontal hairline, face, and chest. Causes It has been hypothesized that the body overreacts to an organism such as the S. aureus bacterium. Diagnosis Treatment There are multiple medications that are able to treat acne varioliformis. Topical * Clindamycin 1% lotion or Benzoyl peroxide/clindamycin gel * Erythromycin 2% gel * 1% hydrocortisone cream Systemic * Doxycycline 50 mg twice daily * Isotretinoin 0.5 mg/kg daily See also * List of cutaneous conditions Many skin conditions affect the human integumentary system—the organ system covering the entire surface ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sycosis Vulgaris
Sycosis vulgaris is a cutaneous condition characterized by a chronic infection of the chin or bearded region. The irritation is caused by a deep infection of hair follicles, often by species of ''Staphylococcus'' or ''Propionibacterium'' bacteria. Asymptomatic or painful and tender erythematous papules and pustules may form around coarse hair in the beard (sycosis barbae) or the back of the neck (sycosis nuchae). See also * Folliculitis * List of cutaneous conditions Many skin conditions affect the human integumentary system—the organ system covering the entire surface of the body and composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against t ... References Bacterium-related cutaneous conditions {{Cutaneous-infection-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tinea Sycosis
Dermatophytosis, also known as ringworm, is a fungal infection of the skin. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. Multiple areas can be affected at a given time. About 40 types of fungus can cause ringworm. They are typically of the ''Trichophyton'', ''Microsporum'', or ''Epidermophyton'' type. Risk factors include using public showers, contact sports such as wrestling, excessive sweating, contact with animals, obesity, and poor immune function. Ringworm can spread from other animals or between people. Diagnosis is often based on the appearance and symptoms. It may be confirmed by either culturing or looking at a skin scraping under a microscope. Prevention is by keeping the skin dry, not walking barefoot in public, and not sharing personal items. Treatment is typically with antifungal creams such as clotrimazole or miconazole. If the scalp is involved, ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varicose
Varicose veins, also known as varicoses, are a medical condition in which superficial veins become enlarged and twisted. These veins typically develop in the legs, just under the skin. Varicose veins usually cause few symptoms. However, some individuals may experience fatigue or pain in the area. Complications can include bleeding or superficial thrombophlebitis. Varices in the scrotum are known as a varicocele, while those around the anus are known as hemorrhoids. Due to the various physical, social, and psychological effects of varicose veins, they can negatively affect one's quality of life. Varicose veins have no specific cause. Risk factors include obesity, lack of exercise, leg trauma, and family history of the condition. They also develop more commonly during pregnancy. Occasionally they result from chronic venous insufficiency. Underlying causes include weak or damaged valves in the veins. They are typically diagnosed by examination, including observation by ultrasound. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burn
A burn is an injury to skin, or other tissues, caused by heat, cold, electricity, chemicals, friction, or ultraviolet radiation (like sunburn). Most burns are due to heat from hot liquids (called scalding), solids, or fire. Burns occur mainly in the home or the workplace. In the home, risks are associated with domestic kitchens, including stoves, flames, and hot liquids. In the workplace, risks are associated with fire and chemical and electric burns. Alcoholism and smoking are other risk factors. Burns can also occur as a result of self-harm or violence between people (assault). Burns that affect only the superficial skin layers are known as superficial or first-degree burns. They appear red without blisters and pain typically lasts around three days. When the injury extends into some of the underlying skin layer, it is a partial-thickness or second-degree burn. Blisters are frequently present and they are often very painful. Healing can require up to eight weeks and scarri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, ''half-life period'', dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to ''half-life'' in the early 1950s. Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radical (chemistry)
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉) which have two unpaired electrons. Radicals may be generated in a number of ways, but typical methods involve redox reactions. Ionizing radiation, heat, electrical discharges, and electrolysis are known to produce radicals. Radicals are intermediates in many chemical reactions, more so than is apparent from the balanced equations. Radicals are important in combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry, and many other chemical processes. A majority of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homolysis (chemistry)
In chemistry, homolysis () or homolytic fission is the dissociation of a molecular bond by a process where each of the fragments (an atom or molecule) retains one of the originally bonded electrons. During homolytic fission of a neutral molecule with an even number of electrons, two free radicals will be generated. That is, the two electrons involved in the original bond are distributed between the two fragment species. Bond cleavage is also possible by a process called heterolysis. The energy involved in this process is called bond dissociation energy (BDE). BDE is defined as the "enthalpy (per mole) required to break a given bond of some specific molecular entity by homolysis," symbolized as ''D''. BDE is dependent on the strength of the bond, which is determined by factors relating to the stability of the resulting radical species. Because of the relatively high energy required to break bonds in this manner, homolysis occurs primarily under certain circumstances: * Light ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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