Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. The degree of crystallinity has a big influence on hardness, density, transparency and diffusion. In a gas, the relative positions of the atoms or molecules are completely random. Amorphous materials, such as liquids and glasses, represent an intermediate case, having order over short distances (a few atomic or molecular spacings) but not over longer distances.

Many materials (such as glass-ceramics and some polymers), can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such cases, crystallinity is usually specified as a percentage of the volume of the material that is crystalline. Even within materials that are completely crystalline, however, the degree of structural perfection can vary. For instance, most metallic alloys are crystalline, but they usually comprise many independent crystalline regions (grains or crystallites) in various orientations separated by grain boundaries; furthermore, they contain other defects (notably dislocations) that reduce the degree of structural perfection. The most highly perfect crystals are silicon boules produced for semiconductor electronics; these are large single crystals (so they have no grain boundaries), are nearly free of dislocations, and have precisely controlled concentrations of defect atoms.

Julian Miles "Jools" Holland OBE, DL (born 24 January 1958) is an English pianist, bandleader, singer, composer, and television presenter. He was a founder of the band Squeeze (1974-1980 & 1985-1990) and his work has involved him with many artists including Sting, Eric Clapton, George Harrison, David Gilmour, Magazine and Bono.

Holland is a published author and appears on television shows besides his own and contributes to radio shows. In 2004, he collaborated with Tom Jones on an album of traditional R&B music. He currently hosts Later... with Jools Holland, a music-based show aired on BBC2, on which his annual show Hootenanny, is based.

His great grandfather came from Ireland.

Holland played as a session musician before finding fame, and his first studio session was with Wayne County & the Electric Chairs in 1976 on their track "F*ck Off."

Holland was a founding member of the British pop band Squeeze, formed in March 1974, in which he played keyboards until 1981 and helped the band to achieve millions of record sales, before pursuing his solo career.

Omar Souleyman is an Arab musician from Ra's al-'Ayn, Syria, in the north eastern region of Syria. He began his career in 1994, working with a number of musicians with whom he still performs, and around five hundred studio and live albums have been released under his name. (Eighty percent of those releases are recordings made at weddings and presented to the married couple, which are later copied and sold at local kiosks.) His music has reached a wider audience in recent years due to the American label Sublime Frequencies, from which he has been able to tour extensively and release three records. He appeared at the Glastonbury Festival in 2011, and performed during Chaos in Tejas in Austin, Texas in June 2011 . Souleyman has been chosen by Caribou to perform at the ATP Nightmare Before Christmas festival that they will co-curate in December 2011 in Minehead, England. In 2011 he recorded three re mixes for Björk's Biophilia, all found on the second disc of her "Crystalline Series".

He performs traditional Middle Eastern songs in Kurdish and Arabic. Gorillaz frontman Damon Albarn confirmed that the band collaborated with Souleyman on a track that did not make their 2010 album Plastic Beach, Albarn said that the track will see a release one day, upon completion.

Matthew Herbert (born 1972), also known as Herbert, Doctor Rockit, Radio Boy, Mr. Vertigo, Transformer, and Wishmountain, is a British electronic musician. He has pioneered the use of so-called 'real', 'ordinary' or 'found' sounds in modern electronic music.

Herbert began experimenting with aleatoric processes while studying drama at Exeter University in the early 1990s. He gave his first professional public performance in 1995 as Wishmountain, reportedly using a bag of crisps as an instrument. Two years of performing under this name followed before he retired Wishmountain in favor of Radio Boy. In addition to creating rhythmic musique concrete as Radio Boy, however, Herbert worked on more traditional, yet relatively experimental dance music.

In the mid 90s he traveled to San Francisco, where he met jazz singer Dani Siciliano. In 1998, Herbert issued Around the House, which successfully mixed dance beats, sounds generated by everyday kitchen objects, and Siciliano's wry vocals. By the late Nineties, Herbert was remixing tracks for dance artists like Moloko, Motorbass, Alter Ego, and others. (Many of these were later collected on Secondhand Sounds: Herbert Remixes.) He also recorded singles, EPs, and albums under a variety of aliases (Doctor Rockit, Radio Boy, Mr. Vertigo, and Transformer) as well as his own name.