Lexikon
basic unit of length, one millionth meter: 1 micron = 0, 000,001 metre, or 1x10-6 m.
The symbol of micron is μm.
It is also called micrometre.
small nuclei, separate from and additional to the main nuclei of cells, produced during telophase of mitosis (meiosis) by lagging chromosome fragments or whole chromosomes. There are two major versions of this test, one in vivo and the other in vitro. The in vivo test normally uses mouse bone marrow or mouse peripheral blood. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage.
a micronucleus test is a test used in toxicological screening for potential genotoxic compounds. There are two major versions of this test, one in vivo and the other in vitro. The in vivo test normally uses mouse bone marrow or mouse peripheral blood. The assay is now recognized as one of the most successful and reliable assays for genotoxic carcinogens, i.e., carcinogens that act by causing genetic damage. The mouse peripheral blood assay has been adapted for measurement by flow cytometry. The first use of micronuclei in cultured cells was in human lymphocytes. The assay has been improved for use in lymphocytes and other cells in culture cells. A micronucleus is the erratic (third) nucleus that is formed during the anaphase of mitosis or meiosis.
Using fluorescent in situ hybridization (FISH) with probes targeted to the centromere region, it can be determined if a whole chromosome, or only a fragment is lost.
mineral water is water containing minerals or other dissolved substances that alter its taste or give it therapeutic value, generally obtained from a naturally occurring mineral spring or source. Dissolved substances in the water may include various salts and sulfur compounds. Mineral water can be sparkling, or still.
The U.S. FDA (Food and Drug Administration) classifies mineral water as water containing at least 250 parts per million total dissolved solids (TDS), originating from a geologically and physically protected underground water source. No minerals may be added to this water.
a mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. Classifying minerals can range from simple to very difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex chemical or X-ray diffraction analysis; these methods, however, can be costly and time-consuming. Physical properties commonly used are: crystal structure and habit, hardness, lustre, colour, streak, cleavage, fracture, specific gravity, other properties (fluorescence (response to ultraviolet light), magnetism, radioactivity, tenacity (response to mechanical induced changes of shape or form), piezoelectricity and reactivity to dilute acids. Minerals may be classified according to chemical composition. The most famous mineral classifiers are the American James Dwight Dana (1813-1895) and the German Karl Hugo Strunz (1910–2006). Strunz in his work „Mineralogische Tabellen” (1941) categorized minerals by anion group. Having as a basis the Dana and Strunz classification systems the current classification scheme divides minerals into nine classes, which are further divided into divisions, families and groups according to chemical composition and crystal structure: 1. Elements; 2.Sulfides and sulfosalts; 3. Halides; 4. Oxides and hydroxides; 5. Carbonates, nitrates and borates; 6. Sulfates, chromates, molybdates and tungstates; 7. Phospates, arsenates and vanadates; 8 Silicates; 9. Organic compounds
microRNA (miRNA) is a recently discovered class of small non-coding RNAs. Cells use miRNA to regulate the amount of protein synthesized by a gene by the mechanisms of translational inhibition and mRNA destabilization (Bushati & Cohen, 2007). Over 250 miRNAs have been discovered.
Source: Bushati, N. & Cohen, S.M. (2007). microRNA functions. Annu. Rev. Cell Dev. Biol. 23, 175−205.
the genetic material found in mitochondria, the organelles that generate energy for the cell.
The mitochondrion has its own independent genome. Not inherited in the same fashion as nucleic DNA and the molecular structure is also different from the chromosomal DNA.
Further, its DNA shows substantial similarity to bacterial genomes. Based on this similarity they are thought to be originally derived from endosymbiotic prokaryotes.
mitosis is the process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.
mode of action
in manufacturing and design, a mock-up or mockup, is a scale or full-size model of a design or device, used for teaching, demonstration, evaluating a design, promotion, and other purposes. A mockup is called a prototype if it provides at least part of the functionality of a system and enables testing of a design.
Monitored Natural Attenuation (MNA) is the monitoring of the effects of naturally occurring physical, chemical, and biological processes or any combination of these processes to reduce the load, concentration, flux or toxicity of polluting substances in soil and groundwater in order to obtain a sustainable remediation objective.
moribound status is a state of the test animal whic was treated by an appropriate dose of the test substance. This animal shows the singns of dying or inability to survive, even if treated.
Moving Picture Experts Group, department of ISO
Material Safety Data Sheet for chemical substances.
An important component of product stewardship and workplace safety, it is intended to provide workers and emergency personnel with procedures for handling or working with that substance in a safe manner, and includes information such as physical data (melting point, boiling point, flash point, etc.), toxicity, health effects, first aid, reactivity, storage, disposal, protective equipment, and spill-handling procedures. MSDS formats can vary from source to source within a country depending on national requirements.
MSDSs are a widely used system for cataloging information on chemicals, chemical compounds, and chemical mixtures. MSDS information may include instructions for the safe use and potential hazards associated with a particular material or product. These data sheets can be found anywhere where chemicals are being used.
There is also a duty to properly label substances on the basis of physico-chemical, health and/or environmental risk. Labels can include hazard symbols such as the European Union standard black diagonal cross on an orange background, used to denote a harmful substance.
The content of MSDS in Europe reflects the requirement of REACH and is called: SDS: Safety Data Sheet. From 2011 all SDS should be prepared according to REACH requirements.
On the website of http://www.sciencelab.com/msdsList.php you can find the link-list of existing 4653 MSDSs of chemical substances: you can download the MSDS of any of the chemical substances enlisted.
Sources:
http://en.wikipedia.org/wiki/Material_safety_data_sheet
http://www.reach-compliance.eu/english/compliance/SDS/SDS.html
http://www.sciencelab.com/msdsList.php
in agriculture and gardening, mulch is a protective cover placed over the soil to retain moisture, reduce erosion, provide nutrients, and suppress weed growth and seed germination. Mulching in gardens and landscaping mimics the leaf cover that is found on forest floors.
Mulch can be prepared from waste material:
forestry waste/byproduct, such as shredded bark, whole bark nuggets, wood chips
agricultural waste/by-product, such as grass clippings, leaves, hay, straw
other waste material of biological origin: shells, wool
cellulose containing waste material such as newspaper or cardboard
rubber mulch: made from recycled tire rubber
ecogravel made from gredged (contaminated) sediment by vitrificatio
waste rock and gravel.
multi-phase extraction uses a vacuum system to remove various combinations of contaminated groundwater, separate-phase petroleum product, and vapors from the subsurface. The system lowers the water table around the well, exposing more of the formation. Contaminants in the newly exposed vadose zone are then accessible to vapor extraction. Once above ground, the extracted vapors or liquid-phase organics and ground water are separated and treated.
Source: US-EPA, Clu-In:http://www.clu-in.org/techfocus/default.focus/sec/Multi-Phase_Extraction/cat/Overview/
mutagenic substances or agents are, those, which induce mutation in living cells. Mutagenicity refers to the induction of permanent transmissible changes in the amount or structure of the genetic material of cells or organisms. These changes may involve a single gene or gene segment, a block of genes or chromosomes.
Alterations to the genetic material of cells may occur spontaneously or be induced as a result of exposure to ionising or ultraviolet radiation, or genotoxic substances. In principle, human exposure to substances that are mutagens may result in increased frequencies of mutations above baseline. Heritable damage to the offspring, and possibly to subsequent generations, of parents exposed to substances that are mutagens may follow if mutations are induced in parental germ cells (reproduction cells). Mutations in somatic cells (cells others than reproduction cells) may be lethal or may be transferred to daughter cells with deleterious consequences for the affected organism. There is considerable evidence of a positive correlation between the mutagenicity of substances in vivo and their carcinogenicity in long-term studies with animals. The aims of testing for mutagenicity are to assess the potential of substances to induce effects which may cause heritable damage in humans or lead to cancer.
Mutagens are usually chemical compounds or ionizing radiation. Mutagens can be divided into different categories according to their effect on DNA replication:
- Some mutagens act as base analogs and get inserted into the DNA strand during replication in place of the substrates.
- Some react with DNA and cause structural changes that lead to miscopying of the template strand when the DNA is replicated.
- Some work indirectly by causing the cells to synthesize chemicals that have the direct mutagenic effect.
mutagenicity refers to the induction of permanent transmissible changes in the amount or structure of the genetic material of cells or organisms. These changes may involve a single gene or gene segment, a block of genes or chromosomes.
Alterations to the genetic material of cells may occur spontaneously or be induced as a result of exposure to ionising or ultraviolet radiation, or genotoxic substances. In principle, human exposure to substances that are mutagens may result in increased frequencies of mutations above baseline. Heritable damage to the offspring, and possibly to subsequent generations, of parents exposed to substances that are mutagens may follow if mutations are induced in parental germ cells (reproduction cells). Mutations in somatic cells (cells others than reproduction cells) may be lethal or may be transferred to daughter cells with deleterious consequences for the affected organism. There is considerable evidence of a positive correlation between the mutagenicity of substances in vivo and their carcinogenicity in long-term studies with animals. The aims of testing for mutagenicity are to assess the potential of substances to induce effects which may cause heritable damage in humans or lead to cancer.
Chemicals are defined as carcinogenic if they induce tumours, increase tumour incidence and/or malignancy or shorten the time to tumour occurrence. Carcinogenic chemicals have conventionally been divided into two categories according to the presumed mode of action. Non-genotoxic modes of action include epigenetic changes, i.e., effects that do not involve alterations in DNA but that may influence gene expression, altered cell-cell communication, or other factors involved in the carcinogenic process. The objective of investigating the carcinogenicity of chemicals is to identify potential human carcinogens, their mode(s) of action, and their potency.
Once a chemical has been identified as a carcinogen, there is a need to elucidate the underlying mode of action, i.e. whether the chemical is directly genotoxic or not. For genotoxic carcinogens it is assumed that, unless exception, there is no discernible threshold and that any level of exposure carries a risk. For non-genotoxic carcinogens, no-effect-thresholds are assumed to exist and to be discernable. Human studies are generally not available for making a distinction between the above mentioned modes of action; and a conclusion on this, in fact, depends on the outcome of mutagenicity testing and other mechanistic studies. In addition to this, animal studies may also inform on the underlying mode of carcinogenic action.
The cancer hazard and mode of action may also be highly dependent on exposure conditions such as the route of exposure. Therefore, all relevant effect data and information on human exposure conditions are evaluated.
Source: REACH
mutations are changes in DNA bases (insertions, deletions, translocations) that may result in changes to the proteins that are synthesized, or even prevent their synthesis. Chemicals that are mutagens can cause permanent heritable changes in the DNA sequence.
The number of mutation events per gene per unit of time (for example, per cell generation). The proportion of mutations per cell divison in bacteriaor other sigle cell organisms, or the proportion of mutations per gamete in higher organisms.