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The bay leaf is an aromatic leaf commonly used as a herb in cooking. It can be used whole, either dried or fresh, in which case it is removed from the dish before consumption, or less commonly used in ground form. The flavor that a bay leaf imparts to a dish has not been universally agreed upon, but many agree it is a subtle addition.
Ultraviolet (UV) light is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.
Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet, visible (400–750 nm), or infrared radiation (750–2500 nm).
Photodynamic therapy (PDT) is a form of phototherapy involving light and a photosensitizing chemical substance used in conjunction with molecular oxygen to elicit cell death (phototoxicity).
Rosacea is a long-term skin condition that typically affects the face. It results in redness, pimples, swelling, and small and superficial dilated blood vessels. Often, the nose, cheeks, forehead, and chin are most involved. A red, enlarged nose may occur in severe disease, a condition known as rhinophyma.
Light sensitivity or photosensitivity refers to a notable or increased reactivity to light. Apart from vision, human beings have many physiological and psychological responses to light. In rare individuals an atypical response may result in serious discomfort, disease, or injury. Some drugs have a photosensitizing effect. Properties of natural or artificial light that may abnormally affect people include:
Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as 1
[O
2] or 1
O
2), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, but the rate of decay is slow.
Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity.
A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.
Verteporfin, a benzoporphyrin derivative, is a medication used as a photosensitizer for photodynamic therapy to eliminate the abnormal blood vessels in the eye associated with conditions such as the wet form of macular degeneration. Verteporfin accumulates in these abnormal blood vessels and, when stimulated by nonthermal red light with a wavelength of 689 nm in the presence of oxygen, produces highly reactive short-lived singlet oxygen and other reactive oxygen radicals, resulting in local damage to the endothelium and blockage of the vessels.
Gas gangrene is a bacterial infection that produces tissue gas in gangrene. This deadly form of gangrene usually is caused by Clostridium perfringens bacteria. About 1,000 cases of gas gangrene are reported yearly in the United States.
Photosensitizers are light absorbers that alter the course of a photochemical reaction. They usually are catalysts. They can function by many mechanisms, sometimes they donate an electron to the substrate, sometimes they abstract a hydrogen atom from the substrate. At the end of this process, the photosensitizer returns to its ground state, where it remains chemically intact, poised to absorb more light. One branch of chemistry which frequently utilizes photosensitizers is polymer chemistry, using photosensitizers in reactions such as photopolymerization, photocrosslinking, and photodegradation. Photosensitizers are also used to generate prolonged excited electronic states in organic molecules with uses in photocatalysis, photon upconversion and photodynamic therapy. Generally, photosensitizers absorb electromagnetic radiation consisting of infrared radiation, visible light radiation, and ultraviolet radiation and transfer absorbed energy into neighboring molecules. This absorption of light is made possible by photosensitizers' large de-localized π-systems, which lowers the energy of HOMO and LUMO orbitals to promote photoexcitation. While many photosensitizers are organic or organometallic compounds, there are also examples of using semiconductor quantum dots as photosensitizers.
Eucalyptol is a monoterpenoid colorless liquid, and a bicyclic ether. It has a fresh camphor-like odor and a spicy, cooling taste. It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up about 70–90% of eucalyptus oil. Eucalyptol forms crystalline adducts with hydrohalic acids, o-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.
Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD).
Photoinhibition is light-induced reduction in the photosynthetic capacity of a plant, alga, or cyanobacterium. Photosystem II (PSII) is more sensitive to light than the rest of the photosynthetic machinery, and most researchers define the term as light-induced damage to PSII. In living organisms, photoinhibited PSII centres are continuously repaired via degradation and synthesis of the D1 protein of the photosynthetic reaction center of PSII. Photoinhibition is also used in a wider sense, as dynamic photoinhibition, to describe all reactions that decrease the efficiency of photosynthesis when plants are exposed to light.
Lupus erythematosus is a collection of autoimmune diseases in which the human immune system becomes hyperactive and attacks healthy tissues. Symptoms of these diseases can affect many different body systems, including joints, skin, kidneys, blood cells, heart, and lungs. The most common and most severe form is systemic lupus erythematosus.
A photocarcinogen is a substance which causes cancer when an organism is exposed to it, then illuminated. Many chemicals that are not carcinogenic can be photocarcinogenic when combined with exposure to light, especially UV. This can easily be understood from a photochemical perspective: The reactivity of a chemical substance itself might be low, but after illumination it transitions to an excited state, which is chemically much more reactive and therefore potentially harmful to biological tissue and DNA. Light can also split photocarcinogens, releasing free radicals, whose unpaired electrons cause them to be extremely reactive.
Photoaging or photoageing is a term used for the characteristic changes to skin induced by chronic UVA and UVB exposure. Tretinoin is the best studied retinoid in the treatment of photoaging.
Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavouring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note.
Cry6Aa is a toxic crystal protein generated by the bacterial family Bacillus thuringiensis during sporulation. This protein is a member of the alpha pore forming toxins family, which gives it insecticidal qualities advantageous in agricultural pest control. Each Cry protein has some level of target specificity; Cry6Aa has specific toxic action against coleopteran insects and nematodes. The corresponding B. thuringiensis gene, cry6aa, is located on bacterial plasmids. Along with several other Cry protein genes, cry6aa can be genetically recombined in Bt corn and Bt cotton so the plants produce specific toxins. Insects are developing resistance to the most commonly inserted proteins like Cry1Ac. Since Cry6Aa proteins function differently than other Cry proteins, they are combined with other proteins to decrease the development of pest resistance. Recent studies suggest this protein functions better in combination with other virulence factors such as other Cry proteins and metalloproteinases.>
References
- ↑ "The Root of It All: Plants to avoid".
- ↑ "Flora of Zimbabwe: Note 2: An encounter with the Blister bush (Diplolophium buchananii)".
- ↑ J. Bakker, F. J. Gommers, I. Nieuwenhuis and H. Wynberg. Photoactivation of the nematicidal compound alpha-terthienyl from roots of marigolds (Tagetes species). A possible singlet oxygen role. JBC, Vol. 254, Issue 6, 1841-1844, Mar, 1979. http://www.jbc.org/cgi/content/abstract/254/6/1841
- ↑ Manish Nivsarkar, Bapu Cherian and Harish Padh. Alpha-terthienyl: A plant-derived new generation insecticide. Current Science, Vol. 81, No. 6, 25 September 2001. http://www.ias.ac.in/currsci/sep252001/667.pdf
