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Crystallography

Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. The word "crystallography" is derived from the Greek words crystallon "cold drop, frozen drop", with its meaning extending to all solids with some degree of transparency, graphein "to write". In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming that 2014 would be the International Year of Crystallography. Before the development of X-ray diffraction crystallography, the study of crystals was based on physical measurements of their geometry using a goniometer; this involved measuring the angles of crystal faces relative to each other and to theoretical reference axes, establishing the symmetry of the crystal in question. The position in 3D space of each crystal face is plotted on a stereographic net such as a Wulff net or Lambert net; the pole to each face is plotted on the net. Each point is labelled with its Miller index; the final plot allows the symmetry of the crystal to be established.

Crystallographic methods now depend on analysis of the diffraction patterns of a sample targeted by a beam of some type. X-rays are most used. Crystallographers explicitly state the type of beam used, as in the terms X-ray crystallography, neutron diffraction and electron diffraction; these three types of radiation interact with the specimen in different ways. X-rays interact with the spatial distribution of electrons in the sample. Electrons are charged particles and therefore interact with the total charge distribution of both the atomic nuclei and the electrons of the sample. Neutrons are scattered by the atomic nuclei through the strong nuclear forces, but in addition, the magnetic moment of neutrons is non-zero, they are therefore scattered by magnetic fields. When neutrons are scattered from hydrogen-containing materials, they produce diffraction patterns with high noise levels. However, the material can sometimes be treated to substitute deuterium for hydrogen; because of these different forms of interaction, the three types of radiation are suitable for different crystallographic studies.

With conventional imaging technique such as optical microscopy, obtaining an image of a small object requires collecting light with a magnifying lens. However, the resolution of any optical system is limited by the diffraction-limit of light, which depends on its wavelength. For example, visible light has a wavelength of about 4000 to 7000 ångström, three orders of magnitude longer than the length of typical atomic bonds and atoms themselves. Therefore, a conventional optical microscope cannot resolve the spatial arrangement of atoms in a crystal. To do so, we would need radiation with much shorter wavelengths, such as neutron beams. Focusing X-rays with conventional optical lens can be a challenge. Scientists have had some success focusing X-rays with microscopic Fresnel zone plates made from gold, by critical-angle reflection inside long tapered capillaries. Diffracted X-ray or neutron beams cannot be focused to produce images, so the sample structure must be reconstructed from the diffraction pattern.

Diffraction pattern arises from the constructive interference of photons, scattered by the periodic, repeating feature of the sample under studies. Because of their ordered and repetitive atomic structure, crystals diffracts x-rays in a coherent manner referred as Bragg's reflection. Coordinates in square brackets such as denote a direction vector. Coordinates in angle brackets or chevrons such as <100> denote a family of directions which are related by symmetry operations. In the cubic crystal system for example, <100> would mean, or the negative of any of those directions. Miller indices in parentheses such as denote a plane of the crystal structure, regular repetitions of that plane with a particular spacing. In the cubic system, the normal to the plane is the direction, but in lower-symmetry cases, the normal to is not parallel to. Indices in curly brackets or braces such as denote a family of planes and their normals. In cubic materials the symmetry makes them equivalent, just as the way angle brackets denote a family of directions.

In non-cubic materials, <hkl> is not perpendicular to. Some materials that have been analyzed crystallographically, such as proteins, do not occur as crystals; such molecules are placed in solution and allowed to crystallize through vapor diffusion. A drop of solution containing the molecule and precipitants is sealed in a container with a reservoir containing a hygroscopic solution. Water in the drop diffuses to the reservoir increasing the concentration and allowing a crystal to form. If the concentration were to rise more the molecule would precipitate out of solution, resulting in disorderly granules rather than an orderly and hence usable crystal. Once a crystal is obtained, data can be collected using a beam of radiation. Although many universities that engage in crystallographic research have their own X-ray producing equipment, synchrotrons are used as X-ray sources, because of the purer and more complete patterns such sources can generate. Synchrotron sources have a much higher intensity of X-ray beams, so data collection takes a fraction of the time necessary at weaker sources.

Complementary neutron crystallography techniques are used to identify the positions of hydrogen atoms, since X-rays only interact weakly with light elements such as hydrogen. Producing an image from a diffraction pattern requires

Kerem Çatay

Kerem Catay is the CEO of Ay Yapım, producer of all series, Turkey’s leading production company for drama series, formats and daily shows. Born in Ankara, Kerem Çatay graduated from Bilkent University Faculty of Economics and Social Sciences, he completed his education in the Film and Television program at UCLA. He is known as the producer of countless phenomenally successful TV series, from 2008’s ground-breaking “Aşk-ı Memnu” to 2009’s “Ezel”. Çatay’s productions are renowned for their well-crafted, captivating stories based on both original screenplays and literary adaptations. Nearly all of Catay’s productions have been sold at least 41 countries, MENA to Sweden, Eastern & Southern Asia, Eastern Europe, the Balkans plus some of the African TV channels, they are made available via Internet Worldwide. Kerem Çatay on IMDb

Square Roots: The Story of SpongeBob SquarePants

Square Roots: The Story of SpongeBob SquarePants is a 2009 American documentary film directed and co-written by Patrick Creadon. The special was released on VH1 on July 14, 2009, was included on SpongeBob SquarePants: The First 100 Episodes DVD released in North America on September 22, 2009; the documentary chronicles the popular culture success of the animated television series SpongeBob SquarePants. It features commentaries from celebrity fans. Square Roots: The Story of SpongeBob SquarePants focuses on the American animated television series SpongeBob SquarePants and its immersion into global popular culture; the film documents the show's early inspirations, its origins. Among the millions of fans are celebrities such as LeBron James and Ricky Gervais, who express their insights for the show and its title character, SpongeBob, it features the series' impact on the US President Barack Obama, the inmates of San Quentin State Prison, fans around the world. Archive footage Square Roots: The Story of SpongeBob SquarePants was directed by Patrick Creadon.

The documentary film aired on television on the cable network VH1 in the United States on July 14, 2009. It aired on Nick at Nite on July 23, 2009, with a TV-PG parental rating, it was first announced in early 2009. On a press release, Viacom told: Commissioned by Nickelodeon to commemorate the anniversary of the series' first episode, the documentary chronicles the beloved character's journey to international pop culture icon status and showcases the series' impact on everyone from President Barack Obama, kids across the globe and San Quentin inmates who sing its catchy theme song; the one-hour documentary, features an opening song from Avril Lavigne and commentary from creator Steve Hillenburg and crew members, industry experts and celebrities like LeBron James, Ricky Gervais and Rosario Dawson. The documentary film was endorsed to mark the celebration of the series' 10th anniversary, following a SpongeBob marathon the next weekend; the anniversary was celebrated with the premiere of the television film SpongeBob's Truth or Square and the special episode "To SquarePants or Not to SquarePants".

On September 22, 2009, the documentary appeared as a bonus feature on the DVD compilation SpongeBob SquarePants: The First 100 Episodes. The DVD runs 2200 minutes long. Other bonus features included in the DVD set are Limited edition etched Plexiglass case, Limited edition 3D lenticular, Audio Commentary from the Animation Team, Life Lessons from Bikini Bottom, "Help Wanted": The Seven Seas Edition, Kick-Wham-Pow-Bob Music Video; the documentary film received positive reviews. David Hinckley of the New York Daily News said that the "documentary's most interesting moments come from Hillenburg, who created SpongeBob as a secondary character in a comic before breaking him out on his own in July 1999." He added that "it's fun for the whole family." R. L. Shaffer of IGN wrote "what's here is still fun to pilfer though and a true delight for longtime fans." Gord Lacey of TV Shows on DVD called the film "the single-best feature that's appeared on a Nickelodeon DVD set." Michael Cavna of The Washington Post called it "some'cult' to have."Aaron H. Bynum of Animation Insider said that it "is of two halves, the first of, where the value lies.

The first twenty minutes or so of the documentary is excellent. He added that the "remainder of the documentary is chiefly fluff." Official website Watch full video Square Roots: The Story of SpongeBob SquarePants on IMDb Square Roots: The Story of SpongeBob SquarePants at TV.com