The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed. Therefore, the quantity of mass is conserved over time; the law implies that mass can neither be created nor destroyed, although it may be rearranged in space, or the entities associated with it may be changed in form. For example, in chemical reactions, the mass of the chemical components before the reaction is equal to the mass of the components after the reaction. Thus, during any chemical reaction and low-energy thermodynamic processes in an isolated system, the total mass of the reactants, or starting materials, must be equal to the mass of the products; the concept of mass conservation is used in many fields such as chemistry and fluid dynamics. Mass conservation was demonstrated in chemical reactions independently by Mikhail Lomonosov and rediscovered by Antoine Lavoisier in the late 18th century.

The formulation of this law was of crucial importance in the progress from alchemy to the modern natural science of chemistry. The conservation of mass only holds and is considered part of a series of assumptions coming from classical mechanics; the law has to be modified to comply with the laws of quantum mechanics and special relativity under the principle of mass-energy equivalence, which states that energy and mass form one conserved quantity. For energetic systems the conservation of mass-only is shown not to hold, as is the case in nuclear reactions and particle-antiparticle annihilation in particle physics. Mass is not conserved in open systems; such is the case when various forms of matter are allowed into, or out of, the system. However, unless radioactivity or nuclear reactions are involved, the amount of energy escaping such systems as heat, mechanical work, or electromagnetic radiation is too small to be measured as a decrease in the mass of the system. For systems where large gravitational fields are involved, general relativity has to be taken into account, where mass-energy conservation becomes a more complex concept, subject to different definitions, neither mass nor energy is as and conserved as is the case in special relativity.

The law of conservation of mass can only be formulated in classical mechanics when the energy scales associated to an isolated system are much smaller than m c 2, where m is the mass of a typical object in the system, measured in the frame of reference where the object is at rest, c is the speed of light. The law can be formulated mathematically in the fields of fluid mechanics and continuum mechanics, where the conservation of mass is expressed using the continuity equation, given in differential form as ∂ ρ ∂ t + ∇ ⋅ = 0, where ρ is the density, t is the time, ∇ ⋅ is the divergence, v is the flow velocity field; the interpretation of the continuity equation for mass is the following: For a given closed surface in the system, the change in time of the mass enclosed by the surface is equal to the mass that traverses the surface, positive if matter goes in and negative if matter goes out. For the whole isolated system, this condition implies that the total mass M, sum of the masses of all components in the system, does not change in time, i.e. d M d t = d d t ∫ ρ d V = 0,where d V is the differential that defines the integral over the whole volume of the system.

The continuity equation for the mass is part of Euler equations of fluid dynamics. Many other convection–diffusion equations describe the conservation and flow of mass and matter in a given system. In chemistry, the calculation of the amount of reactant and products in a chemical reaction, or stoichiometry, is founded on the principle of conservation of mass; the principle implies that during a chemical reaction the total mass of the reactants is equal to the total mass of the products. For example, in the following reaction CH4 + 2 O2 → CO2 + 2 H2O,where one molecule of methane and two oxygen molecules O2 are converted into one molecule of carbon dioxide and two of water; the number of molecules as result from the reaction can be derived from the principle of conservation of mass, as four hydrogen atoms, 4 oxygen atoms and one carbon atom are present the number water molecules produced must be two per molecule of carbon dioxide produced. Many engineering problems are solved by following the mass distribution in time of a given system, this practice is known as mass balance.

An important idea in ancient Greek philosophy was that "Nothing comes from nothing", so that what exists now has always existed: no new matter can come into existence where there was none before. An explicit statement of this

The 1998 FIFA World Cup AFC–OFC qualification play-off was a two-legged home-and-away tie between the winners of the Oceania qualifying tournament and the losing team in the AFC play-off from the Asian qualifying tournament, Iran. The games were played on 29 November 1997 in Tehran and Melbourne respectively. Australia was hoping to play in the FIFA World Cup for the first time since 1974 and Iran in 1978; the second game is known in Australia and in rest of the world as Melbournazo, in Iran as the Saga of Melbourne. Prior to arrival in Tehran, Terry Venables and others involved in the Australian national team had made negative comments about Iran, stating it as being dangerous, going so far as to bring their own drinking water for their stay; the first leg of the play-off, on 22 November 1997, took place in Tehran, with the result a 1–1 draw. Attendance for this match was high, as 128,000 fans packed Azadi Stadium, despite it only having a capacity for 100,000 fans at the time. Full of confidence after this result, the Australian team came to the second leg in Melbourne believing they could progress to their first FIFA World Cup in 24 years.

The second leg, held on 29 November at the Melbourne Cricket Ground, had a crowd of 98,000. With Australia holding a 1–0 lead at half-time and scoring a second goal just after the break, it looked that they would progress to the World Cup. Following Australia's second goal, spectator Peter Hore, known for disrupting major events, ran onto the field and cut up Iran's goal net, causing a halt in play. However, Australia's dominance continued until a controversial booking of Harry Kewell following a collision with Iranian goalkeeper Ahmad Reza Abedzadeh in the 72nd minute; this seemed to quell the Australians' momentum, as an Iranian revival, led by Khodadad Azizi, saw Iran score two quick goals to make the score 3–3 on aggregate, with Iran progressing on away goals. Despite being undefeated throughout their entire qualifying campaign, Australia had again failed to qualify for the World Cup finals. Along with host nation and eventual winner France, Saint Kitts and Nevis, Australia were one of three teams to not lose a game in the entire campaign.

The match is considered by many Australians as the most tragic moment in their sporting history. The broadcast of the game on SBS featured closing comments from a distraught Les Murray and Johnny Warren, with Warren weeping on air. 10th Anniversary of Melbourne Showdown, IranSportsPress.com First leg Second leg

Choerophryne siegfriedi is a species of frog in the family Microhylidae. It is endemic to Papua New Guinea and is only known from its type locality, Mount Elimbari in the Simbu Province; this species was described in the genus Albericus, named for Alberich, the dwarf in Scandinavian mythology and Richard Wagner's opera cycle Der Ring des Nibelungen. Menzies named the species he described after Alberich's companions in the mythodology, in this case Siegfried; the specimens in the type series were reported to measure 14–16 mm in snout–urostyle length. Examination of a subset of these, of which five are females and one is a male, gave much larger size, 18–21 mm in snout–vent length; the reason for this large discrepancy is unknown. The ventral surface is reddish, yellowish, or whitish, with variable spotting or else uniformly dark. Choerophryne siegfriedi is similar to Choerophryne darlingtoni, apart from the call that can be characterized as a "squeak", repeated in irregular series. Choerophryne siegfriedi is known from montane rainforest at 2,400–2,500 m above sea level.

Development is direct. This species was quite common at the type locality, it is threatened by land clearance leading to habitat fragmentation. Bush fires are an additional threat, it is not known to occur in any protected area

Emily Meg Jackson, is a British legal scholar who specialises in medical law. She has been a professor of Law at the London School of Economics since 2007 and Head of its Law Department since 2012, she has researched or lectured at the Faculty of Law, University of Oxford, at St Catharine's College, Cambridge, at Birkbeck College, University of London, at Queen Mary, University of London. Jackson was born on 28 December 1966 in England, to Douglas and Lesley Jackson, she was educated at a state secondary school in Bushey, Hertfordshire. She studied jurisprudence at Oxford, she graduated from the University of Oxford with a Bachelor of Arts degree in 1989. After graduating from university, Jackson began her career as a research officer at the Centre for Socio-Legal Studies, a research institute of the Faculty of Law, University of Oxford. In 1991, she was elected a Fellow of St Catharine's College and appointed a lecturer in law, she moved to Birkbeck College, University of London where she was a lecturer in law from 1993 to 1997.

In 1998, she joined the London School of Economics for the first time having been appointed as a senior lecturer in law. From 2004 to 2007, Jackson was Professor of Medical Law at University of London, she was appointed Professor of Law at the London School of Economics in 2007 and Head of the Law Department in 2012. Jackson has held a number of appointments outside of her university work. From 2003 to 2012, she was a member of the Human Embryology Authority. Since 2005, she has been a member of the Medical Ethics Committee of the British Medical Association. Since 2011, she has been a member of the Medical Research Council's Ethics and Public Involvement Committee. Since 2012, she has been a member of the Ethics Committee of the Royal College of Obstetricians and Gynaecologists. In 2013, she was a member of the Department of Health's Independent Panel led by Julia Neuberger, Baroness Neuberger that reviewed the Liverpool Care Pathway for the Dying Patient. Since February 2014, she has been a member of the Judicial Appointments Commission.

In July 2016, Jackson was elected a Fellow of the British Academy, the UK's national academy for the humanities and the social sciences. She was appointed Officer of the Order of the British Empire in the 2017 Birthday Honours for services to higher education

Candy Chen is a dancer, host, rapper and a model. She is featured on the Taiwanese variety shows: Blackie's Teenage Blackie Lollipop. Candy was a member of the Taiwanese girl group Hey Girl from 2010 to 2011, a member of Twinko from 2013 to 2016, she is 1/8th Dutch. She changed her name to Chen Yi-Ling in July 2012 to follow her mother's maiden name, her English name becomes Nina Chen. In November 2013, she changed her name to Chen Si Ya. 2007-09-14：26th Elimination Match，1st Place. 2007-10-18：27th Elimination Match，1st Place. 09-25：Special Project – 100% Lovely Priestress 11-02：Interrogation Room – Undiscovered Beauty 12–25：Playact Class – How to be a sweety girl 03-11：Home Economics Class – Creative Cuisine Match 07-10：Music Class – In Heart Love Song Prince 07-11：Playact Class – Asian Dancing King 08-13: Beauty's Change 04-02：Queen is Coming – Jolin's Successor Decision Match Channel V 《Pop Beauty Wind》 Beauty Look World – Women Power Beauty Theme Pavilion – Dancing Queen Beauty Theme Pavilion – Excellent Singer to be a Director Beauty KTV Beauty Super Star's Day – Cyndi's Love Songs Day Beauty Theme Pavilion – Live Show Beauty KTV Beauty KTV Beauty Theme Pavilion – Beauty Request Song Beauty KTV Beauty Theme Pavilion – Live Show Beauty Theme Pavilion – Good Girl's Love Song Beauty KTV Beauty Theme Pavilion – Second Shoot Beauty Pop Wind Beauty KTV Beauty Japan Wind 《Pop VJ Wind》 KT Famous Love Song Of Jolin 2 Channel V《Where 5.com》（2008-09-14） Gala Television Corp, GTV《100% Entertainment Blackie Beauties – Old Girls VS New Girls 》（2008-06-06） Lollipop "Lollipop" Live Show （2008-01-26） <FANS> 2008 Feb.（with Hongshi, Bella Cheng and Ruby Lin） Candy's Facebook Candy's Weibo, with her new Chinese name

The Pitkin Glassworks Ruin is a historic industrial archaeological site at the junction of Parker and Putnam Streets in Manchester, Connecticut. It contains the remains of one of the oldest glass factories in New England, established in 1783, it was listed on the National Register of Historic Places in 1979. The Pitkin Glass Factory was established when the area was still considered part of East Hartford, was known at the time as the East Hartford Glass Works. William and Elisha Pitkin had supplied gunpowder to the Continental Army during the American Revolutionary War at a financial loss, petitioned the state in 1783 for an exclusive right to manufacture glass as compensation for their losses; the state granted them a 25-year monopoly. The factory went into operation a few years and soon ran into financial difficulties. Several lotteries were held to raise additional funds, but the endeavour closed its doors in 1830; the factory produced items made of green glass, including demijohns for trade with the West Indies, as well as all manner of utilitarian containers, from inkwells to pitchers and bowls.

It is unclear. The ruins of the structure of the factory are located on what was once the Pitkin Farm, what is the corner of Putnam and Parker Streets. Between the two streets is a grassy plot of land with a sign that identifies it as the former site of the Pitkin Tavern; the site includes remnants of the factory's stone walls, as well as other archaeological remains. The ruined remains of the factory were deed by the Pitkin family to the Daughters of the American Revolution in 1928; the DAR, citing increasing maintenance costs, suggested selling the property for development in 1977. In response to this threat, a committee of citizens formed to save it, they include members of the Manchester Historical Society. Several archaeological digs have taken place on the site, including one done by students at Central Connecticut State University. Displays of artifacts and the history of the site are located in the Old Manchester Museum on Cedar Street. New England Glassworks, founded in 1780 in Temple, New Hampshire National Register of Historic Places listings in Hartford County, Connecticut Pitkin Glass Works web site