Image: Surface of a kidney stone. jpg | SEM image of the surface of a kidney stone showing tetragonal crystals of Weddellite ( calcium oxalate dihydrate ) emerging from the amorphous central part of the stone.

Scanning Electron Micrograph of the surface of a kidney stone showing crystals of Weddellite ( calcium oxalate dihydrate ) emerging from the amorphous central part of the stone.

Weddellite crystals are poorly birefringent and do not show any interference pattern under polarized light.

Weddellite crystals are usually of little clinical value.

* Calcium carbide ( CaC < sub > 2 </ sub >) is used to make acetylene gas ( for use in acetylene torches for welding ) and in the manufacturing of plastics.

Alkali metals, alkaline earth metals, and lanthanoid metals form acetylides, e. g., sodium carbide Na < sub > 2 </ sub > C < sub > 2 </ sub >, calcium carbide CaC < sub > 2 </ sub >, and LaC < sub > 2 </ sub >.

The C-C triple bond length ranges from 109. 2 pm in CaC < sub > 2 </ sub > ( similar to ethyne ), to 130. 3 pm in LaC < sub > 2 </ sub > and 134 pm in UC < sub > 2 </ sub >.

CaC < sub > 2 </ sub >,

CaC < sub > 2 </ sub > O < sub > 4 </ sub >,

For example, whewellite, CaC < sub > 2 </ sub > O < sub > 4 </ sub >⋅ H < sub > 2 </ sub > O is an oxalate that can be deposited in hydrothermal ore veins.

For instance, calcium ion might be precipitated using oxalate ion, to produce calcium oxalate ( CaC < sub > 2 </ sub > O < sub > 4 </ sub >); it might then be heated to convert it into the oxide ( CaO ).

Carbide lamps, or acetylene gas lamps, are simple lamps that produce and burn acetylene ( C < sub > 2 </ sub > H < sub > 2 </ sub >) which is created by the reaction of calcium carbide ( CaC < sub > 2 </ sub >) with water.

Whewellite is a mineral, hydrated calcium oxalate, formula CaC < sub > 2 </ sub > O < sub > 4 </ sub >· H < sub > 2 </ sub > O.

* All other syllabic laryngeals become * a ( CHC > CaC )

The International Time Bureau ( BIH ) began a time scale, T < sub > m </ sub > or AM, in July 1955, using both local caesium clocks and comparisons to distant clocks using the phase of VLF radio signals.

All 128 ASCII characters, including non-printable characters ( represented by their abbreviations ). The 95 ASCII graphic characters are numbered from 20 < sub > hexadecimal | hex </ sub > to 7E < sub > hexadecimal | hex </ sub > ( decimal 32 to 126 ).

The " space " character had to come before graphics to make sorting easier, so it became position 20 < sub > hex </ sub >; for the same reason, many special signs commonly used as separators were placed before digits.

To keep options available for lower case letters and other graphics, the special and numeric codes were arranged before the letters, and the letter " A " was placed in position 41 < sub > hex </ sub > to match the draft of the corresponding British standard.

The @ symbol was not used in continental Europe and the committee expected it would be replaced by an accented À in the French variation, so the @ was placed in position 40 < sub > hex </ sub > next to the letter A.

* If it is required to use a single number X as an estimate for the value of numbers, then the arithmetic mean does this best, in the sense of minimizing the sum of squares ( x < sub > i </ sub > − X )< sup > 2 </ sup > of the residuals.

If F ≥ F < sub > Critical </ sub > ( Numerator DF, Denominator DF, α )

With the formula C < sub > n </ sub > H < sub > 2n + 2 </ sub >, Alkanes belong to a homologous series of organic compounds in which the members differ by a constant relative molecular mass of 14.

Algeria has always been a source of inspiration for different painters who tried to immortalize the prodigious diversity of the sites it offers and the profusion of the facets that passes its population, which offers for Orientalists between the 19 < sup > th </ sup > century and the 20 < sup > th </ sup > century, a striking inspiration for a very rich artistic creation like Eugène Delacroix with his famous painting women of Algiers in their apartment or Etienne Dinet or other painters of world fame like Pablo Picasso with his painting women of Algiers, or painters issued from the Algiers school.

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η < sup > 2 </ sup > ( eta-squared ):

He also offers a conversion table ( see Cohen, 1988, p. 283 ) for eta squared ( η < sup > 2 </ sup >) where 0. 0099 constitutes a small effect, 0. 0588 a medium effect and 0. 1379 a large effect.

When there are only two means to compare, the t-test and the ANOVA F-test are equivalent ; the relation between ANOVA and t is given by F = t < sup > 2 </ sup >.

The number of carbon atoms is used to define the size of the alkane ( e. g., C < sub > 2 </ sub >- alkane ).

: H < sub > 2 </ sub > O ( l ) + H < sub > 2 </ sub > O ( l ) H < sub > 3 </ sub > O < sup >+</ sup >( aq ) + OH < sup >−</ sup >( aq )

In pure water the majority of molecules exist as H < sub > 2 </ sub > O, but a small number of molecules are constantly dissociating and re-associating.

Brackets indicate concentration, such that means the concentration of H < sub > 2 </ sub > O.

This force is used in the formal definition of the ampere, which states that it is " the constant current that will produce an attractive force of 2 × 10 < sup >– 7 </ sup > newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum ".

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Because the clocks had been on average well above sea level, this meant that TAI slowed down, by about 10 < sup >− 12 </ sup >.

The simplest possible alkane ( the parent molecule ) is methane, CH < sub > 4 </ sub >.

The Arrhenius definition states that acids are substances which increase the concentration of hydronium ions ( H < sub > 3 </ sub > O < sup >+</ sup >) in solution.

An Arrhenius acid is a substance that increases the concentration of the hydronium ion, H < sub > 3 </ sub > O < sup >+</ sup >, when dissolved in water.

Note that chemists often write H < sup >+</ sup >( aq ) and refer to the hydrogen ion when describing acid-base reactions but the free hydrogen nucleus, a proton, does not exist alone in water, it exists as the hydronium ion, H < sub > 3 </ sub > O < sup >+</ sup >.

Both theories easily describe the first reaction: CH < sub > 3 </ sub > COOH acts as an Arrhenius acid because it acts as a source of H < sub > 3 </ sub > O < sup >+</ sup > when dissolved in water, and it acts as a Brønsted acid by donating a proton to water.