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Irradiation
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to normal levels of background radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such as infrared, visible light, microwaves from cellular phones or electromagnetic waves emitted by radio and TV receivers and power supplies. Applications Sterilization If administered at appropriate levels, all forms of ionizing radiation can sterilize objects, including medical instruments, disposables such as syringes, and sterilize food. Ionizing radiation ( electron beams, X-rays and gamma rays) may be used to kill bacteria in food or other organic material, including blood. Food irradiation, while effective, is seldom used due to problems with public accep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Irradiation
Food irradiation is the process of exposing food and food packaging to ionizing radiation, such as from gamma rays, x-rays, or electron beams. Food irradiation improves food safety and extends product shelf life (preservation) by effectively destroying organisms responsible for spoilage and foodborne illness, inhibits sprouting or ripening, and is a means of controlling insects and invasive pests. In the US, consumer perception of foods treated with irradiation is more negative than those processed by other means. The U.S. Food and Drug Administration (FDA), the World Health Organization (WHO), the Centers for Disease Control and Prevention (CDC), and U.S. Department of Agriculture (USDA) have performed studies that confirm irradiation to be safe.World Health Organization. Safety and Nutritional Adequacy of Irradiated Food. Geneva, Switzerland: World Health Organization; 1994 In order for a food to be irradiated in the US, the FDA will still require that the specific fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sterilization (microbiology)
Sterilization refers to any process that removes, kills, or deactivates all forms of life (particularly microorganisms such as fungi, bacteria, spores, and unicellular eukaryotic organisms) and other biological agents such as prions present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic. Applications Foods One of the first steps toward modernized sterilization was made by Nicolas Appert, who discovered that application of heat over a suitable period slowed the decay of foods and various liquids, preserving them for safe consumption for a longer time than was typical. Canning of foods is an extension ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Beam Processing
Electron-beam processing or electron irradiation (EBI) is a process that involves using electrons, usually of high energy, to treat an object for a variety of purposes. This may take place under elevated temperatures and nitrogen atmosphere. Possible uses for electron irradiation include sterilization and cross-linking of polymers. Electron energies typically vary from the keV to MeV range, depending on the depth of penetration required. The irradiation dose is usually measured in grays but also in Mrads ( is equivalent to ). The basic components of a typical electron-beam processing device include: an electron gun (consisting of a cathode, grid, and anode), used to generate and accelerate the primary beam; and, a magnetic optical (focusing and deflection) system, used for controlling the way in which the electron beam impinges on the material being processed (the "workpiece"). In operation, the gun cathode is the source of thermally emitted electrons that are both accelerated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Therapy
Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tiss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swift Heavy Ions
Swift heavy ions are the components of a type of particle beam with high enough energy that electronic stopping dominates over nuclear stopping.M. Toulemonde, W. Assmann, C. Dufour, A. Meftah, F. Studer, and C. Trautmann, Experimental phenomena and thermal spike model description of ion tracks in amorphisable inorganic insulators, Mat. Fys. Medd. Kong. Dan. Vid. Selsk. 52, 263 (2006). They are accelerated in particle accelerators to very high energies, typically in the MeV or GeV range and have sufficient energy and mass to penetrate solids on a straight line. In many solids swift heavy ions release sufficient energy to induce permanently modified cylindrical zones, so-called ion tracks. If the irradiation is carried out in an initially crystalline material, ion tracks consist of an amorphous cylinder. Ion tracks can be produced in many amorphizing materials, but not in pure metals, where the high electronic heat conductivity dissipates away the electronic heating before the ion tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exposure (radiation)
Radiation is a moving form of energy, classified into ionizing and non-ionizing type. Ionizing radiation is further categorized into electromagnetic radiation (without matter) and particulate radiation (with matter). Electromagnetic radiation consists of photons, which can be thought of as energy packets, traveling in the form of a wave. Examples of electromagnetic radiation includes X-rays and gamma rays (see photo "Types of Electromagnetic Radiation"). These types of radiation can easily penetrate the human body because of high energy. Radiation exposure is a measure of the ionization of air due to ionizing radiation from photons. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. Medical exposure is defined by the International Commission on Radiological Protection as exposure incurred by patients as part of their own medical or dental diagnosis or treatment; by persons, other than those occupationally expos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionizing Radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum. Gamma rays, X-rays, and the higher energy ultraviolet part of the electromagnetic spectrum are ionizing radiation, whereas the lower energy ultraviolet, visible light, nearly all types of laser light, infrared, microwaves, and radio waves are non-ionizing radiation. The boundary between ionizing and non-ionizing radiation in the ultraviolet area is not sharply defined, as different molecules and atoms ionize at different energies. The energy of ionizing radiation starts between 10 electronvolts (eV) and 33 eV. Typical ionizing subatomic particles include alpha particles, beta particles, and neutrons. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Transfusion
Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but modern medical practice commonly uses only components of the blood, such as red blood cells, white blood cells, plasma, clotting factors and platelets. Red blood cells (RBC) contain hemoglobin, and supply the cells of the body with oxygen. White blood cells are not commonly used during transfusion, but they are part of the immune system, and also fight infections. Plasma is the "yellowish" liquid part of blood, which acts as a buffer, and contains proteins and important substances needed for the body's overall health. Platelets are involved in blood clotting, preventing the body from bleeding. Before these components were known, doctors believed that blood was homogeneous. Because of this scientific misunderstanding, many patients died ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Implantation
Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fabrication and in metal finishing, as well as in materials science research. The ions can alter the elemental composition of the target (if the ions differ in composition from the target) if they stop and remain in the target. Ion implantation also causes chemical and physical changes when the ions impinge on the target at high energy. The crystal structure of the target can be damaged or even destroyed by the energetic collision cascades, and ions of sufficiently high energy (10s of MeV) can cause nuclear transmutation. General principle Ion implantation equipment typically consists of an ion source, where ions of the desired element are produced, an accelerator, where the ions are electrostatically accelerated to a high energy, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Rays
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts ( keV) to approximately 8 megaelectronvolts ( MeV), corresponding to the typical energy levels in nuclei with reasonably long ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Implantation
Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fabrication and in metal finishing, as well as in materials science research. The ions can alter the elemental composition of the target (if the ions differ in composition from the target) if they stop and remain in the target. Ion implantation also causes chemical and physical changes when the ions impinge on the target at high energy. The crystal structure of the target can be damaged or even destroyed by the energetic collision cascades, and ions of sufficiently high energy (10s of MeV) can cause nuclear transmutation. General principle Ion implantation equipment typically consists of an ion source, where ions of the desired element are produced, an accelerator, where the ions are electrostatically accelerated to a high energy, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heptamethine Dyes
Heptamethine dyes are a subclass of chemical compounds within the cyanine dye family and have many uses as fluorescent dyes, particularly in biomedical imaging, the development of theranostics, the individualized treatment of cancerous patients with the aid of PDT, co-administration with other drugs, and irradiation.F. Pene, E. Courtine, A. Cariou, J.P. Mira. Toward theranostics. Crit Care Med, 37 (2009), pp. S50–S58 The characteristics of heptamethine dyes can be understood by comparing research data on different dyes within the family. For example, the IR-780 dye exhibits a peak spectral absorption of around 780 nm. Optical properties The absorption and fluorescence spectrum of heptamethine dyes are in the near infrared region and vary largely on the solvent and concentration. IR-808 absorbs mainly between 775 nm and 796 nm and emits fluorescence between 808 nm and 827 nm with a large red shift as expected in the serum sample. These absorption ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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