Vented balance safety enclosures are used in pharmaceutical, chemical, biological, and toxicological laboratories to provide maximum containment for weighing operations in weighing scales. Fume hoods, also known as laboratory chemical hoods, are one of the most important and widely used engineering controls to protect workers in laboratories. Fume hoods were introduced about 100 years ago to safeguard personnel working with hazardous materials. While many changes and improvements have been made, the basic concept and design of fume hoods remains the same. Air is drawn from the workplace, around the worker and into the front of the hood, and is then exhausted out of the laboratory.
vented balance enclosureschemical hoods
A salt bridge, in electrochemistry, is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell (voltaic cell), a type of electrochemical cell. It maintains electrical neutrality within the internal circuit, preventing the cell from rapidly running its reaction to equilibrium. If no salt bridge were present, the solution in one half cell would accumulate negative charge and the solution in the other half cell would accumulate positive charge as the reaction proceeded, quickly preventing further reaction, and hence production of electricity. Salt bridges usually come in two types: glass tube and filter paper.
standard potentialstandard cell potentialstandard reduction potentials
Shuttleworth, SJ (1820) Electrochemistry (50th ed.), Harper Collins. Standard Electrode Potentials table. Redox Equilibria. Chemistry of Batteries. Electrochemical Cells. STEP in Non-aqueous solvent.
Justicescales of justiceblind justice
The scales represent the weighing of evidence, and the scales lack a foundation in order to signify that evidence should stand on its own. Since the 16th century, Lady Justice has often been depicted wearing a blindfold. The blindfold represents impartiality, the ideal that justice should be applied without regard to wealth, power, or other status. The earliest Roman coins depicted Justitia with the sword in one hand and the scale in the other, but with her eyes uncovered. Justitia was only commonly represented as "blind" since the middle of the 16th century.
The following techniques are related to electrolysis: * Electrochemical cells, including the hydrogen fuel cell, use differences in Standard electrode potential to generate an electrical potential that provides useful power. Though related via the interaction of ions andelectrolysis and the operation of electrochemical cells are quite distinct. However, a chemical cell should not be seen as performing electrolysis in reverse. In 1832, Michael Faraday reported that the quantity of elements separated by passing an electric current through a molten or dissolved salt is proportional to the quantity of electric charge passed through the circuit.
Cell voltagecell potentialE'' 0
Electrode potential, E, in chemistry or electrochemistry, according to a IUPAC definition, is the electromotive force of a cell built of two electrodes: The SHE is defined to have a potential of 0 V, so the signed cell potential from the above setup is :E cell = E left (SHE) − E right = 0 V − E electrode = E electrode. SHE is cathode and electrode is anode Electrode potential appears at the interface between an electrode and electrolyte due to the transfer of charged species across the interface, specific adsorption of ions at the interface, and specific adsorption/orientation of polar molecules, including those of the solvent.
Electrodes for chemical analysis using electrochemical methods. Inert electrodes for electrolysis (made of platinum). Membrane electrode assembly. Electrodes for Taser electroshock weapon. Working electrode. Reference electrode. Gas diffusion electrode. Cellulose electrode. Battery. Redox (Reduction-Oxidation Reaction). Cathodic protection. Galvanic cell. Anion vs. Cation. Electron versus hole. Electrolyte. Electron microscope. Noryl. Tafel equation. Hot cathode. Cold cathode. Electrolysis. Reversible charge injection limit.
Liquid mercury is a part of popular secondary reference electrode (called the calomel electrode) in electrochemistry as an alternative to the standard hydrogen electrode. The calomel electrode is used to work out the electrode potential of half cells. Last, but not least, the triple point of mercury, −38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (ITS-90). In polarography both the dropping mercury electrode and the hanging mercury drop electrode use elemental mercury. This use allows a new uncontaminated electrode to be available for each measurement or each new experiment.
free energyfree energiesfree-energy
., for electrochemical cells, or f dx work in elastic materials and in muscle contraction. Other forms of work which must sometimes be considered are stress-strain, magnetic, as in adiabatic demagnetization used in the approach to absolute zero, and work due to electric polarization. These are described by tensors. In most cases of interest there are internal degrees of freedom and processes, such as chemical reactions and phase transitions, which create entropy. Even for homogeneous "bulk" materials, the free energy functions depend on the (often suppressed) composition, as do all proper thermodynamic potentials (extensive functions), including the internal energy.
The severity of disease is based on body mass index (BMI) in adults with mild disease having a BMI of greater than 17, moderate a BMI of 16 to 17, severe a BMI of 15 to 16, and extreme a BMI less than 15. In children a BMI for age percentile of less than the 5th percentile is often used. Treatment of anorexia involves restoring a healthy weight, treating the underlying psychological problems, and addressing behaviors that promote the problem. While medications do not help with weight gain, they may be used to help with associated anxiety or depression.
A number of lifestyle factors are known to be important to the development of type 2 DM, including obesity (defined by a body mass index of greater than 30), lack of physical activity, poor diet, stress, and urbanization. Excess body fat is associated with 30% of cases in those of Chinese and Japanese descent, 60–80% of cases in those of European and African descent, and 100% of Pima Indians and Pacific Islanders. Even those who are not obese often have a high waist–hip ratio. Dietary factors also influence the risk of developing type 2 DM. Consumption of sugar-sweetened drinks in excess is associated with an increased risk.
type 2 diabetestype II diabetestype 2 diabetes mellitus
Lifestyle factors are important to the development of type 2 diabetes, including obesity and being overweight (defined by a body mass index of greater than 25), lack of physical activity, poor diet, stress, and urbanization. Excess body fat is associated with 30% of cases in those of Chinese and Japanese descent, 60–80% of cases in those of European and African descent, and 100% of cases in Pima Indians and Pacific Islanders. Among those who are not obese, a high waist–hip ratio is often present. Smoking appears to increase the risk of type 2 diabetes mellitus. Dietary factors also influence the risk of developing type 2 diabetes.
A static equilibrium between two forces is the most usual way of measuring forces, using simple devices such as weighing scales and spring balances. For example, an object suspended on a vertical spring scale experiences the force of gravity acting on the object balanced by a force applied by the "spring reaction force", which equals the object's weight. Using such tools, some quantitative force laws were discovered: that the force of gravity is proportional to volume for objects of constant density (widely exploited for millennia to define standard weights); Archimedes' principle for buoyancy; Archimedes' analysis of the lever; Boyle's law for gas pressure; and Hooke's law for springs.
virtual instrumentsvirtual instrument
The software enables complex and expensive hardware to be replaced by already purchased computer hardware; e. g. analog-to-digital converter can act as a hardware complement of a virtual oscilloscope, a potentiostat enables frequency response acquisition and analysis in electrochemical impedance spectroscopy with virtual instrumentation. The concept of a synthetic instrument is a subset of the virtual instrument concept. A synthetic instrument is a kind of virtual instrument that is purely software defined. A synthetic instrument performs a specific synthesis, analysis, or measurement function on completely generic, measurement agnostic hardware.
OIMLInternational Organization of Legal Metrology (OIML)Convention establishing an International Organization of Legal Metrology
TC 5 General requirements for measuring instruments (2 SCs). TC 6 Prepackaged products. TC 7 Measuring instruments for length and associated quantities (4 SCs). TC 8 Measurement of quantities of fluids (5 SCs). TC 9 Instruments for measuring mass and density (4 SCs). TC 10 Instruments for measuring pressure, force and associated quantities (5 SCs). TC 11 Instruments for measuring temperature and associated quantities (3 SCs). TC 12 Instruments for measuring electrical quantities. TC 13 Measuring instruments for acoustics and vibration. TC 14 Measuring instruments used for optics. TC 15 Measuring instruments for ionizing radiations (2 SCs).
Electrochemical cell. Lemon battery. Thermogalvanic cell. Bioelectrochemical reactor. Biological cell voltage. Bio-nano generator. Cell notation. Desulfation. Electrochemical engineering. Electrode potential. Electrohydrogenesis. Electrosynthesis. Enzymatic biofuel cell. Galvanic series. Isotope electrochemistry. List of battery types. Sacrificial anode. How to build a galvanic cell battery from MiniScience.com. Galvanic Cell, an animation. Interactive animation of Galvanic Cell. Chemical Education Research Group, Iowa State University.
oxidation numberoxidation statesoxidation
Dr. Ancel Keys
In a 1972 article, Keys and his coauthors promoted Adolphe Quetelet's body mass index (BMI) as the best of various indices of obesity, which the U.S. National Institutes of Health then popularized in 1985. Keys was always considered an interventionist. He generally shunned food fads and vigorously promoted the benefits of the "reasonably low-fat diets" he contrasted with "the North American habit for making the stomach the garbage disposal unit for a long list of harmful foods." Because of his influence in dietary science, Keys was featured on the cover of the January 13, 1961 issue of Time magazine. Some doctors and nutritionists have been critical of Keys' implications.
Although the instruments are straightforward to use, careful attention to the method of use (as described by the manufacturer) should be given. Simple devices to estimate body fat, often using BIA, are available to consumers as body fat meters. These instruments are generally regarded as being less accurate than those used clinically or in nutritional and medical practice. They tend to under-read body fat percentage. Dehydration is a recognized factor affecting BIA measurements as it causes an increase in the body's electrical resistance, so has been measured to cause a 5 kg underestimation of fat-free mass i.e. an overestimation of body fat.
fluidstwo-fluid theorytwo-fluid theory'' of electricity
History of electrochemistry.
RobervalGilles Personne de Robervalde Roberval, Gilles
Gilles Personne de Roberval (August 10, 1602 – October 27, 1675), French mathematician, was born at Roberval near Beauvais, France. His name was originally Gilles Personne or Gilles Personier, with Roberval the place of his birth.
The angle of rotation is then read from a scale. The same phenomenon is observed after an angle of 180°. The specific rotation of the sample may then be calculated. Temperature can affect the rotation of light, which should be accounted for in the calculations. where: * Ellipsometry [α] λ T is the specific rotation. T is the temperature. λ is the wavelength of light. α is the angle of rotation. l is the length of the polarimeter tube. \rho is the mass concentration of solution. Polariscope - Gemstone Buzz instrument to measure optical properties. EU Project NanoCharM nanocharm.org.
Johann RitterRitter, Johann Wilhelm
In 1802 he built his first electrochemical cell, with 50 copper discs separated by cardboard disks moistened by a salt solution. Ritter made several self-experiments applying the poles of a voltaic pile to his own hands, eyes, ears, nose and tongue. He also described the difference between the physiological effects of the two poles of the pile, although some of the effects he reported were not confirmed afterwards. Many of Ritter's researches were guided by a search for polarities in the several "forces" of nature, and for the relation between those "forces" – two of the assumptions of Naturphilosophie.
The rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen. The iron is the reducing agent (gives up electrons) while the oxygen is the oxidising agent (gains electrons). The rate of corrosion is affected by water and accelerated by electrolytes, as illustrated by the effects of road salt on the corrosion of automobiles. The key reaction is the reduction of oxygen: :O 2 + 4 + 2 → 4 Because it forms hydroxide ions, this process is strongly affected by the presence of acid. Indeed, the corrosion of most metals by oxygen is accelerated at low pH.