"Vickers hardness test The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness tests since the required calculations are independent of the size of the indenter, and the indenter can be used for all materials irrespective of hardness. The basic principle, as with all common measures of hardness, is to observe the questioned material's ability to resist plastic deformation from a standard source. The Vickers test can"
"test, performed with either 3 gf or 9 gf loads, preceded the development of microhardness testers using traditional indenters. In 1925, Smith and Sandland of the UK developed an indentation test that employed a square-based pyramidal indenter made from diamond. They chose the pyramidal shape with an angle of 136° between opposite faces in order to obtain hardness numbers that would be as close as possible to Brinell hardness numbers for the specimen. The Vickers test has a great advantage of using one hardness scale to test all materials.The first reference to the Vickers indenter with low loads was made"
"of 320 – 330 °C. This indacene has shown to be an organic light-emitting diode that may have important applications for low-cost light displays in commercial industry. The Smith-modified Madelung synthesis, also called the Smith indole synthesis, was discovered in 1986 by Amos Smith and his research team. This synthesis employs a condensation reaction of organolithium reagents derived from 2-alkyl-N-trimethylsilyl anilines by esters or carboxylic acids to yield substituted indoles. This synthesis has proven applicable to a wide variety of substituted anilines, including those with alkyl, methoxy, and halide groups, and can react with non-enolizable esters or lactones to yield"
"0.6%). The accuracy of the measured value of has increased only modestly since the original Cavendish experiment. Measurements with pendulums were made by Francesco Carlini (1821, ), Edward Sabine (1827, ) Carlo Ignazio Giulio (1841, ) and George Biddell Airy (1854, ). Cavendish's experiment was first repeated by Ferdinand Reich (1838, 1842, 1853), who found a value of , which is actually worse than Cavendish's result, differing from the modern value by 1.5%. Cornu and Baille (1873), found . Cavendish's experiment proved to result in more reliable measurements than pendulum experiments of the ""Schiehallion"" (deflection) type or ""Peruvian"" (period as"
"different solution was found in 1964 by Hafner who used a tapered tube (conical: slightly larger at the top). In 1959, Taylor used a column of mercury oscillating inside a U-shaped tube instead of the Rüchardt sphere. In 1964, Donnally and Jensen used a variable load attached to the Rüchardt sphere in order to allows frequency measurements with different oscillating mass. In 1967, Lerner suggested a modified version of the Taylor method (with mercury replaced by water). In 1979, Smith reported a simplified version of the complex Rüchardt-resonance method, originally invented by Clark and Katz, in which an oscillating magnetic"
"involving pendulums continued to be performed in the first half of the 19th century. By the second half of the century, these were outperformed by repetitions of the Cavendish experiment, and the modern value of ""G"" (and hence, of the Earth mass) is still derived from high-precision repetitions of the Cavendish experiment. In 1821, Francesco Carlini determined a density value of ρ = through measurements made with pendulums in the Milan area. This value was refined in 1827 by Edward Sabine to , and then in 1841 by Carlo Ignazio Giulio to . On the other hand, George Biddell Airy"
"bulk metal deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness testers. The differential depth hardness measurement was conceived in 1908 by a Viennese professor Paul Ludwik in his book ""Die Kegelprobe"" (crudely, ""the cone test""). The differential-depth method subtracted out the errors associated with the mechanical imperfections of the system, such as backlash and surface imperfections. The Brinell hardness test, invented in Sweden, was developed earlier – in 1900 – but it was slow, not useful on fully hardened steel, and left too large an impression to be considered nondestructive. Hugh M. Rockwell (1890–1957) and Stanley P."
"classic experiment to improve the accuracy of the calculation. The school experiment uses glycerine as the fluid, and the technique is used industrially to check the viscosity of fluids used in processes. It includes many different oils, and polymer liquids such as solutions. In 1851, George Gabriel Stokes derived an expression for the frictional force (also called drag force) exerted on spherical objects with very small Reynolds numbers (e.g., very small particles) in a continuous viscous fluid by changing the small fluid-mass limit of the generally unsolvable Navier-Stokes equations: where: If the particles are falling in the viscous fluid by"
"pressure associated with changes in arterial function, for example compliance and impedance. Physiological or therapeutic changes in vessel diameter are assumed to reflect changes in ""Q"". PP methods measure the combined performance of the heart and the blood vessels, thus limiting their application for measurement of ""Q"". This can be partially compensated for by intermittent calibration of the waveform to another ""Q"" measurement method then monitoring the PP waveform. Ideally, the PP waveform should be calibrated on a beat-to-beat basis. There are invasive and non-invasive methods of measuring PP. In 1967, the Czech physiologist Jan Peňáz invented and patented the"
"Bicinchoninic acid assay The bicinchoninic acid assay (BCA assay), also known as the Smith assay, after its inventor, Paul K. Smith at the Pierce Chemical Company, is a biochemical assay for determining the total concentration of protein in a solution (0.5 μg/mL to 1.5 mg/mL), similar to Lowry protein assay, Bradford protein assay or biuret reagent. The total protein concentration is exhibited by a color change of the sample solution from green to purple in proportion to protein concentration, which can then be measured using colorimetric techniques. A stock BCA solution contains the following ingredients in a highly alkaline solution"
"in the annual report of the National Physical Laboratory in 1932. Lips and Sack describes the first Vickers tester using low loads in 1936. There is some disagreement in the literature regarding the load range applicable to microhardness testing. ASTM Specification E384, for example, states that the load range for microhardness testing is 1 to 1000 gf. For loads of 1 kgf and below, the Vickers hardness (HV) is calculated with an equation, wherein load (""L"") is in grams force and the mean of two diagonals (""d"") is in millimeters: formula_1 For any given load, the hardness increases rapidly at"
"Bloom (test) Bloom is a test to measure the strength of a gel or gelatin. The test was originally developed and patented in 1925 by Oscar T. Bloom. The test determines the weight in grams needed by a specified plunger (normally with a diameter of 0.5 inch) to depress the surface of the gel by 4 mm without breaking it at a specified temperature. The number of grams is called the Bloom value, and most gelatins are between 30 and 300 g Bloom. The higher a Bloom value, the higher the melting and gelling points of a gel, and the"
"content of 2 litres of expired air was a little greater than that of 1 cc of urine. However, research into the possibilities of using breath to test for alcohol in a person's body dates as far back as 1874, when Francis E. Anstie made the observation that small amounts of alcohol were excreted in breath. Also, in 1927 a Chicago chemist, William Duncan McNally, invented a breathalyzer in which the breath moving through chemicals in water would change color. One use for his invention was for housewives to test whether their husbands had been drinking. In late 1927, in"
"by visual observations. The two main pressure scales used in static high-pressure experiments are X-ray diffraction of a material with a known equation of state and measuring the shift in ruby fluorescence lines. The first began with NaCl, for which the compressibility has been determined by first principles in 1968. The major pitfall of this method of measuring pressure is that you need X-rays. Many experiments do not require X-rays and this presents a major inconvenience to conduct both the intended experiment and a diffraction experiment. In 1971, the NBS high pressure group was set in pursuit of a spectroscopic"
"known as a state cipher, the stream cipher was invented in 1917 by Gilbert Sandford Vernam at Bell Labs. 1917 Marshmallow creme 1918 Superheterodyne receiver 1918 French dip sandwich 1918 Torque wrench 1918 Crystal oscillator 1918 Grocery bag 1918 Hydraulic brake 1919 Blender 1919 Silica gel 1919 Toaster (pop-up) 1920 Eskimo Pie 1920 Jungle gym 1921 Polygraph Not to be confused with an earlier and different invention with the same name, a polygraph, popularly referred to as a lie detector, is an instrument that measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while"
"could be conducted and after further examination it was shown that Stielow's firearm could not have fired the bullets recovered from the victims. The invention of the comparison microscope by Calvin Goddard and Phillip O. Gravelle in 1925 modernized the forensic examination of firearms. Simultaneous comparison of two different objects at the same time allowed to closely examine striations for matches and therefore make a more definitive statement as to whether or not they matched. One of the first true tests of this new technology was in the aftermath of the Saint Valentine's Day Massacre in 1929. During the Prohibition"
"test is that it is less sensitive to the applied load, especially compared to the Brinell hardness test. For cold worked materials the Meyer hardness is relatively constant and independent of load, whereas for the Brinell hardness test it decreases with higher loads. For annealed materials the Meyer hardness increases continuously with load due to strain hardening. Based on Meyer's law hardness values from this test can be converted into Brinell hardness values, and vice versa. The Meyer hardness test was devised by Eugene Meyer of the Materials Testing Laboratory at the Imperial School of Technology, Charlottenburg, Germany, circa 1908."
"remained at that post until 1914. Brinell was elected a member of the Royal Swedish Academy of Sciences in 1902, and of the Royal Swedish Academy of Engineering Sciences in 1919. He died in 1925 in Stockholm. Brinell is best known today for the Brinell hardness test, which he proposed in 1900. In this test a 10-millimetre diameter hardened steel or carbide ball is pushed into the surface of the material being tested, with a 3000 kg imposed load. The depth to which the ball penetrates the material surface is an indication of the ""Brinell Hardness Number"", which is calculated"
"as 5% mannitol, and an intravenous iodine contrast. The location of obstruction can be determined with a Whittaker (or pressure perfusion) test, wherein the collecting system of the kidney is accessed percutaneously, and the liquid is introduced at high pressure and constant rate of 10ml/min while measuring the pressure within the renal pelvis. A rise in pressure above 22 cm HO suggests that the urinary collection system is obstructed. When arriving at this pressure measurement, bladder pressure is subtracted from the initial reading of internal pressure. (The test was first described by Whittaker in 1973 to test the hypothesis that"
"William Nylander (botanist) in 1866. The three most common spot tests are: Although the above tests are most common, a KC test may be performed by wetting the thallus with K followed immediately by C. In addition, Lugol’s iodine may be useful in identifying certain species. Spot tests are performed by placing a small amount of the desired reagent on the portion of the lichen to be tested. Often, both the cortex and medulla of the lichen are tested, and at times it is useful to test other structures such as soralia. One method is to draw up a small"
"of semiconductors. Apker was also active in the field of vacuum science. In 1948 he developed the flash filament method for measuring very low pressures, which was the first widely used method for measuring pressures less than formula_1 Torr. In this method, a gas is allowed to adsorb onto a clean tungsten filament for a set amount of time, and the filament is then rapidly heated. The gas adsorbed onto the filament is released, and the resulting pressure burst can be measured. Though very time consuming, the flash filament method was later used for thermal desorption spectroscopy. Apker followed up"
"developed with Michael W. Hunkapiller, then a research fellow at Caltech. The instrument makes use of the chemical process known as the Edman degradation, devised by Pehr Edman. Edman and Begg's 1967 design involves placing a protein or peptide sample into a spinning cup in a temperature controlled chamber. Reagents are added to cleave the protein one amino acid at the time, followed by solvents to allow extraction of reagents and byproducts. A series of analysis cycles is performed to identify a sequence, one cycle for each amino acid, and the cycle times were lengthy. Hood and Hunkapiller made a"
"lowest glycemic index. Similar findings were reported in the Black Women's Health Study. A diet program that manages the glycemic load aims to avoid sustained blood-sugar spikes and can help avoid onset of type 2 diabetes. For diabetics, glycemic load is a highly recommended tool for managing blood sugar. The data on GI and GL listed in this article is from the University of Sydney (Human Nutrition Unit) GI database. The GI was invented in 1981 by Dr Thomas Wolever and Dr David Jenkins at the University of Toronto and is a measure of how quickly a food containing 25"
"for 25 years. Chick and Lister Institute director Charles James Martin discovered that the process of protein denaturation was distinct from protein coagulation (or flocculation), beginning the modern understanding of protein folding. She is known for having formulated ""Chick's Law"" in 1908, giving the relationship between the kill efficiency of organisms and contact time with a disinfectant. Chick's Law was later modified by Dr. H.E. Watson in 1908 to include the coefficient of specific lethality. The Chick-Watson Equation is still used. A new and, at the time, more realistic test for the effectiveness of disinfectants, the Chick-Martin test, was also"
"can be applied with heavier loads as macroindentation tests: In microindentation testing, the hardness number is based on measurements made of the indent formed in the surface of the test specimen. The hardness number is based on the applied force divided by the surface area of the indent itself, giving hardness units in kgf/mm². Microindentation hardness testing can be done using Vickers as well as Knoop indenters. For the Vickers test, both the diagonals are measured and the average value is used to compute the Vickers pyramid number. In the Knoop test, only the longer diagonal is measured, and the"
"Rowland ring Rowland's ring (aka Rowland ring) is an experimental arrangement for the measurement of the hysteresis curve of a sample of magnetic material. It was developed by Henry Augustus Rowland. The geometry of a Rowland's ring is usually a toroid of magnetic material around which is closely wound a magnetization coil consisting of a large number of windings to magnetize the material, and a sampling coil consisting of a smaller number of windings to sample the induced magnetic flux. The electric current flowing in the magnetization coil dictates the magnetic field intensity formula_1 in the material. The sampling coil"
"also unable to produce the pure compound in any large amount, and found that the purification process diminished its effectiveness and negated the anti-bacterial properties it had. Howard Florey, Ernst Chain, Norman Heatley, Edward Abraham, also all at Oxford, continued the work. They enhanced and developed the concentration technique by using organic solutions rather than water, and created the ""Oxford Unit"" to measure penicillin concentration within a solution. They managed to purify the solution, increasing its concentration by 45–50 times, but found that a higher concentration was possible. Experiments were conducted and the results published in 1941, though the quantities"
"appears towards the end of the book. The ""k""-calculus method had previously been used by E. A. Milne in 1935. Milne used the letter formula_4 to denote a constant Doppler factor, but also considered a more general case involving non-inertial motion (and therefore a varying Doppler factor). Bondi used the letter formula_1 instead of formula_4 and simplified the presentation (for constant formula_1 only), and introduced the name """"k""-calculus"". Consider two inertial observers, Alice and Bob, moving directly away from each other at constant relative velocity. Alice sends a flash of blue light towards Bob once every formula_8 seconds, as measured"
"experiment was performed by Albert A. Michelson and Edward W. Morley at what is now Case Western Reserve University. It is generally considered to be the evidence against the theory of a luminiferous aether. The experiment has also been referred to as ""the kicking-off point for the theoretical aspects of the Second Scientific Revolution."" Primarily for this work, Michelson was awarded the Nobel Prize in 1907. Dayton Miller continued with experiments, conducting thousands of measurements and eventually developing the most accurate interferometer in the world at that time. Miller and others, such as Morley, continue observations and experiments dealing with"
"Bead test The bead test is a traditional part of qualitative inorganic analysis to test for the presence of certain metals. The oldest one is the borax bead test or blister test. It was introduced by Berzelius in 1812. Since then other salts were used as fluxing agents, such as sodium carbonate or sodium fluoride. The most important one after borax is microcosmic salt, which is the basis of the microcosmic salt bead test. A small loop is made in the end of a platinum or Nichrome wire is (as used in the flame test) (or another inert substance like"
"It is also inhibited by the presence of detergents, although this problem can be alleviated by the addition of cyclodextrins to the assay mixture. Much of the non-linearity stems from the equilibrium between two different forms of the dye which is perturbed by adding the protein. The Bradford assay linearizes by measuring the ratio of the absorbances, 595 over 450 nm. This modified Bradford assay is approximately 10 times more sensitive than the conventional one. The Coomassie Blue G250 dye used to bind to the proteins in the original Bradford method readily binds to arginine and lysine groups of proteins."
"vitro nucleic acid amplification (PCR tests) are currently considered the most reliable. Nested PCR test has high sensitivity, but is susceptible to contamination leading to false positive results. The latest real-time PCR tests are rapid, easy to perform, and as sensitive as nested PCR, and have a lower risk of contamination. They also have more sensitivity than viral cultures. Shingles can be confused with herpes simplex, dermatitis herpetiformis and impetigo, and skin reactions caused by contact dermatitis, candidiasis, certain drugs and insect bites. The varicella zoster virus can spread through direct contact with herpes zoster lesions which have not yet"
"1662, the Irish physicist and chemist Robert Boyle performed a series of experiments employing a J-shaped glass tube, which was sealed on one end. Mercury was added to the tube, trapping a fixed quantity of air in the short, sealed end of the tube. Then the volume of gas was measured as additional mercury was added to the tube. The pressure of the gas could be determined by the difference between the mercury level in the short end of the tube and that in the long, open end. Through these experiments, Boyle noted that the gas volume varied inversely with"