An agar plate is a Petri dish that contains agar as a solid growth medium plus nutrients, used to culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. Individual microorganisms placed on the plate will grow into individual colonies, each a clone genetically identical to the individual ancestor organism. Thus, the plate can be used either to estimate the concentration of organisms in a liquid culture or a suitable dilution of that culture using a colony counter, or to generate genetically pure cultures from a mixed culture of genetically different organisms. Several methods are available to plate out cells. One technique is known as "streaking". In this technique, a drop of the culture on the end of a thin, sterile loop of wire, sometimes known as an inoculator, is streaked across the surface of the agar leaving organisms behind, a higher number at the beginning of the streak and a lower number at the end. At some point during a successful "streak", the number of organisms deposited will be such that distinct individual colonies will grow in that area which may be removed for further culturing, using another sterile loop.
Another way of plating organisms, next to streaking, on agar plates is the spot analysis. This type of analysis is used to check the viability of cells and performed with pinners. A third used technique is the use of sterile glass beads to plate out cells. In this technique cells are grown in a liquid culture of which a small volume is pipetted on the agar plate and spread out with the beads. Replica plating is another technique; these four techniques are the most common, but others are possible. It is crucial to work in a sterile manner. Plating is thus done in a laminar flow cabinet or on the working bench next to a bunsen burner. In 1881, Fanny Hesse, working as a technician for her husband Walther Hesse in the laboratory of Robert Koch, suggested agar as an effective setting agent, since it had been commonplace in jam making for some time. Like other growth media, the formulations of agar used in plates may be classified as either "defined" or "undefined". Agar plates may be formulated as either permissive, with the intent of allowing the growth of whatever organisms are present, or restrictive or selective, with the intent of only allowing growth a particular subset of those organisms.
This may take the form of a nutritional requirement, for instance providing a particular compound such as lactose as the only source of carbon and thereby selecting only organisms which can metabolize that compound, or by including a particular antibiotic or other substance to select only organisms which are resistant to that substance. This correlates to some degree with undefined media. Agar plates may be indicator plates, in which the organisms are not selected on the basis of growth, but are instead distinguished by a color change in some colonies caused by the action of an enzyme on some compound added to the medium; the plates are incubated for 12 hours up to several days depending on the test, performed. Some used agar plate types are: Blood agar plates contain mammalian blood at a concentration of 5–10%. BAPs are enriched, differential media used to isolate fastidious organisms and detect hemolytic activity. Β-Hemolytic activity will show lysis and complete digestion of red blood cell contents surrounding a colony.
Examples include Streptococcus haemolyticus. Α-Hemolysis will only cause partial lysis of the red blood cells and will appear green or brown, due to the conversion of hemoglobin to methemoglobin. An example of this would be Streptococcus viridans. Γ-Hemolysis is the term referring to a lack of hemolytic activity. BAPs contain meat extract, sodium chloride, agar. Chocolate agar is a type of blood agar plate in which the blood cells have been lysed by heating the cells to 56 °C, it is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae. No chocolate is contained in the plate. Horse blood agar is a type of blood-enriched microbiological culture media; as it is enriched, it allows the growth of certain fastidious bacteria, allows indication of haemolytic activity in these bacterial cultures. Thayer-Martin agar is a chocolate agar designed to isolate Neisseria gonorrhoeae. Thiosulfate-citrate-bile salts-sucrose agar enhances growth of Vibrio spp. including Vibrio cholerae.
Bile esculin agar is used for the isolation of Enterococcus and group D Streptococcus species CLED agar – cysteine, electrolyte-deficient agar is used to isolate and differentiate urinary tract bacteria, since it inhibits Proteus species swarming and can differentiate between lactose fermenters and nonfermenters. Granada medium is used to isolate and differentiate group B Streptococcus, Streptococcus agalactiae from clinical samples, it grows in Granada medium as most of accompanying bacteria are inhibited. Hektoen enteric agar is designed to is
Test tube holder
A test tube holder is used to hold test tubes. It should not be touched. For example, a test tube holder can be used to hold a test tube. Moreover, when heating the tube with liquid or solid contained inside, the tube holder ought to hold a test tube in order for the tube to be safely held while heating. For liquid heating, when holding a test tube holder with a test tube, hold it such that it aligns with the lab bench and point the open end of the tube away from yourself or anyone nearby. Additionally, while using a test tube holder, the proper distance between the test tube holder and the top of the test tube is 3 centimetres. Structurally, jaws of a test tube holder are self-closed by a spring; the purpose of a test tube holder is to be used only to hold a test tube as it is not structured for flasks or other heavier objects. Test tube Test tube rack
Arthur D. Little
Arthur D. Little is an international management consulting firm headquartered in Boston, United States, formally incorporated by that name in 1909 by Arthur Dehon Little, an MIT chemist who had discovered acetate. Arthur D. Little pioneered the concept of contracted professional services; the company played key roles in the development of business strategy, operations research, the word processor, the first synthetic penicillin, LexisNexis, SABRE and NASDAQ. Today the company is a multi-national management consulting firm operating as a partnership; the roots of the company were started in 1886 by Arthur Dehon Little, an MIT chemist, co-worker Roger B. Griffin, another chemist and a graduate of the University of Vermont who had met when they both worked for Richmond Paper Company, their new company, Little & Griffin, was located in Boston where MIT was located. Griffin and Little prepared a manuscript for The Chemistry of Paper-making, for many years an authoritative text in the area; the book had not been finished when Griffin was killed in a laboratory accident in 1893.
Little, who had studied Chemistry at MIT, collaborated with MIT and William Hultz Walker of the MIT Chemistry department, forming a partnership, Little & Walker, which lasted from 1900 to 1905, while both MIT and Little's company were still located in Boston. The partnership dissolved in 1905 when Walker dedicated all of his time to being in charge of the new Research Laboratory of Applied Chemistry at MIT. Little continued on his own and formally incorporated the company, Arthur D. Little, in 1909, he conducted analytical studies, the precursor of the consulting studies for which the firm would become famous. He taught papermaking at MIT from 1893 to 1916. In 1917, the company based at 103 Milk Street in Boston, moved to a building of its own, the Arthur D. Little Inc. Building, at 30 Memorial Drive on the Charles River next to the new campus of MIT, which had relocated from Boston to Cambridge; the building was added to the National Register of Historic Places in 1976. In November 1953, ADL opened a 40-acre site for its Acorn Park labs in west Cambridge, about 6 miles from MIT.
The new site took its name from the company motto - "Glandes Sparge Ut Quercus Crescant," translated as "Scatter Acorns That Oaks May Grow." The Memorial Drive Trust, a tax-exempt retirement trust for the benefit of its employees, was set up. From 1972 to 2001 ADL owned Cambridge Consultants Ltd in Cambridge UK and both companies forged close links; as the pioneer firm in professional services, Arthur D. Little played a key role in numerous 20th-century business initiatives: In 1911 ADL organized General Motors' first R&D lab, leading to the formation of the firm's dedicated management consulting division, the birth of the management consulting industry. In 1916 ADL was commissioned by the Canadian Pacific Railway to do a survey of Canada's natural resources. In 1921 the firm succeeded in using a bucket of sows' ears to make a silk purse; this revolutionary achievement became part of the Smithsonian Institute's collection. In 1968 ADL designed the NASDAQ stock exchange systems for Tokyo. In 1980, ADL produced the European Commission's first white paper on telecommunications deregulation, having completed the first worldwide telecommunications database on phones installed, technical trends and regulatory information.
It helped privatize British Rail regarded as one of the most complex privatization exercises in the world. By 2001, Arthur D. Little reached its peak as a global consulting firm. However, a new management team mismanaged the company's core business and engaged in manipulation of the Memorial Drive Trust; the ADL Board of Trustees replaced this management team. However, the damage had been done, Arthur D. Little filed Chapter 11 bankruptcy protection in 2002. At an auction in 2002, Paris-based Altran Technologies bought the non-U. S. Assets and brand name of Arthur D. Little. Under Altran's ownership, Arthur D. Little operated as a European-centric company rebuilding and strengthening its core practices in oil and gas, telecommunications, automotive and chemicals. ADL grew and expanded throughout Europe, the Middle East, Asia and continued to be recognized for its expertise in areas combining aspects of technology and strategy. A group of partners led a management buyout from the Altran group in 2011.
The MBO was completed on 30 December 2011 with the vast majority of ADL directors becoming partners and shareholders. A small number of principals, as well as the CFO and COO, are shareholders; the firm is led by the elected Global CEO, Ignacio Garcia-Alves, the leader of the MBO team. The firm operates with an elected board of directors and several elected committees - Compensation Committee, Partnership Committee, an Audit Committee. Since the MBO, ADL opened new offices in Turkey, Buenos Aires and Hong Kong. In addition, ADL re-established itself in the US market and has opened offices in Boston, New York, San Francisco. Arthur D. Little is organized across a number of industry specialty groups including Automotive, Energy / Utilities / Chemicals, Telecommunication / Information / Media / Electronics, Consumer Goods & Retail, Healthcare & Life Sciences, Engineering / Manufacturing, Public Services, Travel & Transportation. Major service lines are in Strategy & Organization, Technology Innovation Management, Operations Management, Risk/Safety.
In 2019, Arthur D. Little is rated #10 and #11 in Vault's 2019 Consulting rankings for Europe and Asia respectively. ADL re-established itself
A shaker is a piece of laboratory equipment used to mix, blend, or agitate substances in a tube or flask by shaking them. It is used in the fields of chemistry and biology. A shaker contains an oscillating board, used to place the flasks, beakers, or test tubes. Although the magnetic stirrer has come to replace the shaker, it is still the preferred choice of equipment when dealing with large volume substances or when simultaneous agitation is required. Invented by Jack A. Kraft and Harold D. Kraft in 1962, a vortex shaker is a small device used to shake or mix small vials of liquid substance, its most standout characteristic is that it works by the user putting a vial on the shaking platform and turning it on. A vortex shaker is variable in terms of speed adjustment, for the shaking speed can be continuously changed while shaking by turning a switch. A platform shaker has a table board; the liquids to be stirred are held in beakers, jars, or erlenmeyer flasks that are placed over the table or, sometimes, in test tubes or vials that are nested into holes in the plate.
Platform shakers can be combined with other systems like rotating mixers for small systems and have been designed to be manufactured in laboratories themselves with open source scientific equipment. An orbital shaker has a circular shaking motion with a slow speed, it is suitable for culturing microbes, washing blots, general mixing. Some of its characteristics are that it does not create vibrations, it produces low heat compared to other kinds of shakers, which makes it ideal for culturing microbes. Moreover, it can be modified by placing it in an incubator to create an incubator shaker due to its low temperature and vibrations. An incubator shaker can be considered a mix of a shaker, it has an ability to shake while maintaining optimal conditions for incubating microbes or DNA replications. This equipment is useful since, in order for a cell to grow, it needs oxygen and nutrients that require shaking so that they can be distributed evenly around the culture. Magnetic stirrer Vortex mixer Stirring rod Static mixer
Sewage treatment is the process of removing contaminants from municipal wastewater, containing household sewage plus some industrial wastewater. Physical and biological processes are used to remove contaminants and produce treated wastewater, safe enough for release into the environment. A by-product of sewage treatment is a semi-solid slurry, called sewage sludge; the sludge has to undergo further treatment before being suitable for disposal or application to land. Sewage treatment may be referred to as wastewater treatment. However, the latter is a broader term which can refer to industrial wastewater. For most cities, the sewer system will carry a proportion of industrial effluent to the sewage treatment plant which has received pre-treatment at the factories themselves to reduce the pollutant load. If the sewer system is a combined sewer it will carry urban runoff to the sewage treatment plant. Sewage water can travel towards treatment plants via piping and in a flow aided by gravity and pumps.
The first part of filtration of sewage includes a bar screen to filter solids and large objects which are collected in dumpsters and disposed of in landfills. Fat and grease is removed before the primary treatment of sewage; the term "sewage treatment plant" is nowadays replaced with the term wastewater treatment plant or wastewater treatment station. Sewage can be treated close to where the sewage is created, which may be called a "decentralized" system or an "on-site" system. Alternatively, sewage can be collected and transported by a network of pipes and pump stations to a municipal treatment plant; this is called a "centralized" system. Sewage is generated by residential, institutional and industrial establishments, it includes household waste liquid from toilets, showers and sinks draining into sewers. In many areas, sewage includes liquid waste from industry and commerce; the separation and draining of household waste into greywater and blackwater is becoming more common in the developed world, with treated greywater being permitted to be used for watering plants or recycled for flushing toilets.
Sewage may include urban runoff. Sewerage systems capable of handling storm water are known as combined sewer systems; this design was common when urban sewerage systems were first developed, in the late 19th and early 20th centuries. Combined sewers require more expensive treatment facilities than sanitary sewers. Heavy volumes of storm runoff may overwhelm the sewage treatment system, causing a spill or overflow. Sanitary sewers are much smaller than combined sewers, they are not designed to transport stormwater. Backups of raw sewage can occur if excessive infiltration/inflow is allowed into a sanitary sewer system. Communities that have urbanized in the mid-20th century or generally have built separate systems for sewage and stormwater, because precipitation causes varying flows, reducing sewage treatment plant efficiency; as rainfall travels over roofs and the ground, it may pick up various contaminants including soil particles and other sediment, heavy metals, organic compounds, animal waste, oil and grease.
Some jurisdictions require stormwater to receive some level of treatment before being discharged directly into waterways. Examples of treatment processes used for stormwater include retention basins, buried vaults with various kinds of media filters, vortex separators. In regulated developed countries, industrial effluent receives at least pretreatment if not full treatment at the factories themselves to reduce the pollutant load, before discharge to the sewer; this process is called pretreatment. The same does not apply to many developing countries where industrial effluent is more to enter the sewer if it exists, or the receiving water body, without pretreatment. Industrial wastewater may contain pollutants which cannot be removed by conventional sewage treatment. Variable flow of industrial waste associated with production cycles may upset the population dynamics of biological treatment units, such as the activated sludge process. Sewage collection and treatment in the United States is subject to local and federal regulations and standards.
Treating wastewater has the aim to produce an effluent that will do as little harm as possible when discharged to the surrounding environment, thereby preventing pollution compared to releasing untreated wastewater into the environment. Sewage treatment involves three stages, called primary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil and lighter solids float to the surface; the settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment. Some sewage treatment plants that are connected to a combined sewer system have a bypass arrangement after the primary treatment unit; this means that during heavy rainfall events, the secondary and tertiary treatment systems can be bypassed to protect them from hydraulic overloading, the mixture of sewage and stormwater only receives primary treatment. Secondary treatment removes suspended biological matter.
Secondary treatment is performed by indigenous, water-borne micro-organisms in a managed habitat. Seconda