Boron trioxide is one of the oxides of boron. It is a white, glassy solid with the formula B2O3, it is always found as the vitreous form. Glassy boron oxide is thought to be composed of boroxol rings which are six-membered rings composed of alternating 3-coordinate boron and 2-coordinate oxygen; because of the difficulty of building disordered models at the correct density with many boroxol rings, this view was controversial, but such models have been constructed and exhibit properties in excellent agreement with experiment. It is now recognized, from experimental and theoretical studies, that the fraction of boron atoms belonging to boroxol rings in glassy B2O3 is somewhere between 0.73 and 0.83, with 0.75 corresponding to a 1:1 ratio between ring and non-ring units. The number of boroxol rings decays in the liquid state with increasing temperature; the crystalline form is composed of BO3 triangles. This trigonal, quartz-like network undergoes a coesite-like transformation to monoclinic β-B2O3 at several gigapascals.
Boron trioxide is produced by treating borax with sulfuric acid in a fusion furnace. At temperatures above 750 °C, the molten boron oxide layer separates out from sodium sulfate, it is decanted and obtained in 96–97% purity. Another method is heating boric acid above ~300 °C. Boric acid will decompose into steam, metaboric acid at around 170 °C, further heating above 300 °C will produce more steam and boron trioxide; the reactions are: H3BO3 → HBO2 + H2O2 HBO2 → B2O3 + H2OBoric acid goes to anhydrous microcrystalline B2O3 in a heated fluidized bed. Controlled heating rate avoids gumming as water evolves. Molten boron oxide attacks silicates. Internally graphitized tubes via acetylene thermal decomposition are passivated. Crystallization of molten α-B2O3 at ambient pressure is kinetically disfavored. Threshold conditions for crystallization of the amorphous solid are 10 kbar and ~200 °C, its proposed crystal structure in enantiomorphic space groups P31. Boron oxide will form when diborane reacts with oxygen in the air or trace amounts of moisture: 2B2H6 + 3O2 → 2B2O3 + 6H2B2H6 + 3H2O → B2O3 + 6H2 Fluxing agent for glass and enamels Starting material for synthesizing other boron compounds such as boron carbide An additive used in glass fibres Component used in the production of borosilicate glass The inert capping layer in the Liquid Encapsulation Czochralski process for the production of gallium arsenide single crystal As an acid catalyst in organic synthesis boron suboxide boric acid sassolite Tris borate National Pollutant Inventory: Boron and compounds Australian Government information US NIH hazard information.
See NIH. Material Safety Data Sheet CDC - NIOSH Pocket Guide to Chemical Hazards - Boron oxide
The Ankylosing Spondylitis Quality of Life questionnaire is a patient-reported outcome measure which assesses the quality of life of patients with ankylosing spondylitis. The ASQoL is based on the needs-based quality of life model, it is a self-administered questionnaire which contains 18 items and takes up to four minutes to complete. Developed by Galen Research and published in 2003, the ASQoL has been used in clinical studies worldwide; the content for the measure was drawn from qualitative interviews that were conducted with ankylosing spondylitis patients. The draft version of the ASQoL was created and went through several stages of testing to ensure it had good face validity, content validity and construct validity; the ASQoL was developed in UK English and Dutch, but to date a total of 37 language versions have been adapted. The language adaptations can be broken down into waves: Pharmaceutical companies began utilizing the ASQoL to test the effectiveness of newly developed TNF inhibitors, which aid in the treatment of ankylosing spondylitis.
Abbott has utilized the ASQoL to evaluate the impact of adalimumab and other organizations like Wyeth and the Medical Research Council have used it to evaluate the effect of etanercept. Since the development of the ASQoL, several studies have been performed in order to evaluate and validate the measure; these studies include: Validation studies for different language versions of the ASQoL which found good reliability and validity
Donovan Alexander is a former professional Canadian football defensive back. He was drafted by the Montreal Alouettes in the third round of the 2007 CFL Draft, he was signed by the Seattle Seahawks as an undrafted free agent in 2008 and upon his release, signed with the Alouettes that same year. He played for the Saskatchewan Roughriders for two seasons and the Edmonton Eskimos for three before signing with Winnipeg. In 2012, he was named a West All-Star with the Eskimos, he played college football at North Dakota. He retired in November, 2014, he was born to Marilyn Alexander. He played high school football for the St. Paul Crusaders of Winnipeg, he is now pursuing a career as an educator at École Leila North Middle School, in Winnipeg Manitoba. He is coaching their grade 8 girls basketball team. Winnipeg Blue Bombers' bio North Dakota Fighting Sioux bio