KNSD, virtual channel 39, is an NBC owned-and-operated television station licensed to San Diego, United States. Owned by the NBC Owned Television Stations subsidiary of NBCUniversal, it is sister to Poway-licensed Telemundo owned-and-operated station KUAN-LD; the two stations share studios on Granite Ridge Drive in the Serra Mesa section of San Diego and transmitter facilities southeast of Spring Valley. KNSD's on-air branding, NBC 7 San Diego, is derived from its cable channel position in the market on Spectrum, Cox Communications and AT&T U-verse; the station is available on channel 39 on satellite providers DirecTV and Dish Network. The station first signed on the air on November 14, 1965, as KAAR, it was the first television station in the San Diego market to operate on the UHF band and was the market's first independent station. The station operated from a building, once occupied by the National Pen Company, located in the neighborhood of Kearny Mesa, 10 miles northeast of downtown San Diego.

Broadcasting from 12 noon to either midnight or 12:30 a.m. the station aired a mix of local and first-run syndicated programming, both vintage and more recent films, reruns of several 1950s dramatic series. However, in the summer of 1966, KAAR cut its operating hours with sign-on time moved up to 5 p.m. and by that fall, the station was only broadcasting on weeknights with a 15-minute 7 p.m. newscast, a travelogue and a movie. A short time in January 1967, KAAR made an arrangement with San Diego State College to air programming produced by the San Diego Area Instructional Television Authority from 9 a.m. to 4 p.m. daily, followed by two hours of cartoons. Channel 39 went dark and was subsequently sold to Western Telecasters Inc. controlled by the Texas-based Bass family, returned to the air on February 2, 1968, as KCST. For a four-year period from the late 1960s to the early 1970s, Western Telecasters tried to take the ABC affiliation from XETV –a station licensed across the Mexican border in Tijuana but which broadcast in English, with a studio facility based in San Diego.

XETV had been San Diego's ABC affiliate since 1956 under a special arrangement between the Federal Communications Commission and Mexican authorities, subject to renewal by the Commission every year. Upon the FCC granting its annual renewal to ABC/XETV in late 1968, Western Telecasters countered, claiming that the presence of KCST made it no longer necessary for an American television network to affiliate with a Mexican television station. In May 1972, the FCC revoked XETV's permission to carry ABC programming; as the only commercial station in the market other than CBS affiliate KFMB-TV and then-NBC affiliate KGTV, KCST took over the ABC affiliation in two stages: daytime programming moved to channel 39 in June 1973, followed by prime time programs and all other shows by July 1, 1973. Four months earlier in March, Western Telecasters agreed to sell KCST to Storer Broadcasting, which owned major network affiliates in the Eastern and Midwestern United States; the sale was completed on September 30, 1974.

The switch and sale changed channel 39's fortunes, transforming the low-rated independent into a major player in the market. Riding on the heels of ABC's ascent to first place nationally during the 1975-76 season, KCST out-rated its network-affiliated rivals locally. XETV, operated as an independent station until October 1986, when it became a charter affiliate of the Fox Broadcasting Company. On June 27, 1977, in the wake of its new success as the highest-rated television network in America, ABC moved its San Diego affiliation from KCST to KGTV, causing an affiliation swap that ended with KCST taking the NBC affiliation held by KGTV. In 1985, the Storer stations were acquired by Kohlberg Kravis Roberts & Co.. Two years KCST and the other Storer stations were sold to Gillett Communications. On September 16, 1988, the station changed its news brand to News San Diego, its call letters to KNSD to reflect the new name. Gillett was restructured into SCI TV in 1991. After SCI filed for Chapter 11 bankruptcy in 1992, the company's stations were sold in a group deal to New World Communications.

New World subsequently entered into a deal with News Corporation that would result in most of New World's television stations switching from their "Big Three" network affiliations to join Fox, causing the network's affiliations in the affected markets relocating from UHF to VHF stations. However, KNSD retained its NBC affiliation since Fox's San Diego affiliation was on the VHF band through XETV. New World sold KNSD and WVTM-TV in Birmingham, Alabama to NBC in May 1996. Following the sale's closure, in January 1997, KNSD modified its on-air branding to "NBC 7/39". In October 1997, NBC sold a 24% ownership interest in KNSD to LIN Television.

Glass disease

Glass disease referred to as sick glass or glass illness, is a degradation process of glass that can result in weeping, spalling and fragmentation. Glass disease is caused by an inherent instability in the chemical composition of the original glass formula. Properties of a particular glass will vary with the type and proportions of silica and alkaline earth in its composition. Once damage has occurred it is irreversible, but decay processes can be slowed by climate control to regulate surrounding temperature and air flow. Glass disease is caused by an inherent fault in the chemical composition of the original glass formula. Glass contains three types of components: network formers establish basic structure, network stabilizers make glass strong and water resistant, flux lowers the melting point at which the glass can be formed. Common formulations of glass may include silica as a former, alkali oxides such as soda or potash for flux, alkaline earth oxides such as lime for stabilizing. Structurally, glass is composed of a network of SiO4-tetrahedrons.

In addition to the network former silicon which establishes its principal structure, glass contains network modifying agents such as the alkali ions Na+ and K+ and the alkali earth ions Ca2+ and Mg2+. Glass does not have a defined stoichiometry, it can incorporate other ions, depending upon factors such as the main composition and firing conditions of the glass. This causes all glass to be chemically unstable to some extent. Electron charge differences of ions within the structure form the basis of its bonding. Both viscosity and transition temperature are related to the availability of oxygen bonds in the glass's composition. Modifying agents tend to lower the melting point of the silica. Higher contents of SiO2 increase acidity of the glass. Higher contents of CaO, Na2O, K2O increase basicity; the chemical stability of glass decreases when only Na2O and K2O are added as flux, because bonding becomes weaker. The chemical stability of glass can be increased by adding CaO, MgO, ZnO, Al2O3. To be stable, glass composition must balance temperature lowering agents with stabilizing agents.

Exposure of a glass surface to moisture, either in solution or from humidity in the atmosphere, causes chemical reactions to occur on and below the surface of the glass. The exchange of alkali metal ions and hydrogen ions can cause chemical and structural changes to the glass; when alkali metal cations in the near-surface layer are replaced by smaller hydrogen ions, structural differences between the affected surface layer and the unaffected lower layers of glass cause increasing tensile stress, which in turn can cause cracking. The likelihood of degradation due to glass disease depends on the amount and proportion of alkaline compounds mixed with silica, on surrounding conditions. Inadequate calcium oxide causes the alkalis in the glass to remain water-soluble at a low level of humidity. Exposure to higher levels of relative humidity during storage or display causes alkali to hydrate and leach out of the glass. Repeated changes in humidity can be damaging, it is important to realize that any glass object can deteriorate if it is exposed to unsuitable environmental conditions.

Crystal, historic glass, or treasured family items should never be exposed to the high temperatures and water pressure of a dishwasher. Energy dispersive x-ray analysis, scanning electron microscopy and secondary ion mass spectrometry can be used to study exchange reactions in different types of glass. By quantifying and studying chemical structure and reactions at the near-surface layer, the mechanisms of glass disease can be better understood. Measurement of the pH of glass surfaces is important if glass objects have a matte surface, or have been exposed to kaolin or other substances. In the case of small objects such as glass beads, pH measurement may be necessary to determine whether alkaline salts are present and changes in the glass are occurring; the processes involved in glass disease can reduce the transparency of the glass or threaten the integrity of the structure. Glass disease causes a complex disintegration of the glass which can be identified through a variety of symptoms, including weeping, spalling and fragmentation.

The following description of glass beads from an object in the collection of the British Museum illustrates the range of symptoms that can occur with glass disease: "Two factors indicated that the deterioration was the result of the phenomenon referred to as ‘glass disease’. This included the presence of small white crystals on the surface of most pale yellow beads and a fine network of uniform cracks or ‘crizzling’ crossing the surface of 55 of the 69 beads; this crizzling appeared to be more prevalent around the bead holes. A total of 32 beads had areas of spalling, or advanced crizzling, where cracks had extended further into the glass structure... Many had areas that had spalled and the fragments lost. Vertical cracks extending through the glass were present on 37 beads and four beads had become detached due to complete fragmentation." The initial stage of glass disease occurs when moisture causes alkali to be leached out of the glass. This becomes apparent when hygroscopic alkali deposits on the glass give it a cloudy or hazy appearance.

This may occur within as little as five to 10 years of the glass's manufacturing. The glass may feel slippery or

Grafton High School (Virginia)

Grafton High School is a public high school located in Grafton, an unincorporated section of York County, Virginia. It is part of the York County School Division; the school opened on September 3, 1996 and shares a facility with Grafton Middle School, the only shared facility of this type in the Hampton Roads area, the largest building in York County at the time of its construction. Athletic teams compete in the Virginia High School League's AA Bay Rivers, in Region I. Grafton High School was awarded a silver medal by U. S. News & World Report in the 2008 America’s Best High Schools search. On February 3, 2020 an electrical fire broke out at the school complex just before 4pm, shutting the school down. Classes at both schools were moved to local Tabb York High, respectively. Students and teachers from Grafton use those buildings on Tuesday’s, Thursday’s, Saturday’s. Grafton High is accredited by the Virginia State Department of Education and has been accredited by the Southern Association of Colleges and Schools since its inception in 1996.

Grafton High fields varsity teams in these sports: Grafton has seven team state titles, one in field hockey one in boys outdoor track four in competition cheer and one in men's swimming. Grafton has individual AA state champions in Boys Cross Country, Boys Indoor Track, Girls Outdoor Track,Boys Outdoor Track, Girls Swimming, Boys Tennis, Wrestling. Two club sports and Girls lacrosse, are offered by the school. 2010 Boys Outdoor Track Team The Grafton High School Boys Track Team were awarded the 2010 VHSL AA Outdoor State Team Championship after placing 4th at the State Cross-Country Championships and only getting a 5th place spot during the Indoor Track season. The boys were able to earn a 1st Place podium spot. Point scorers for Grafton were: Kyle King – 16pts, Dwayne Stover – 13.5pts, David Gunnerson – 10pts, Brian Gorwitz – 7pts. Members who ran this weekend were: Brian Wilmer, Brian Gorwitz, David Gunnerson, Paul Tyler, Rehan Talibi, Ben Hoppe, Conor Wallace, Kyle King, Matt Garcia and Dwayne Stover.

Notable performances include:Kyle King 2nd, Brian Gorwitz 7th in the 3200mIn the 4x800 Meter Relay – 11th Dwayne Stover – tied for 5th place in the High Jump, David Gunnerson 3rd, Brian Gorwitz 4th in the 1600m, Dwayne Stover 1st – the only individual champion of the weekend in the 400m, Kyle King 2nd, David Gunnerson 5th in the 800m, 4x400 Meter Relay – 12th. All these athletes made it possible for the Clippers to get onto the team podium for the first time in the history of Grafton High School. Grafton High School has three bands: Concert Band, Symphonic Band, Wind Ensemble. Grafton has a Jazz Band and Percussion Ensemble. Grafton has a marching band; the marching band is class AAAAA. The band has been a Virginia Honor Band for the past 14 years; the following elementary schools feed into GHS: Coventry Elementary School Dare Elementary School Grafton-Bethel Elementary School All residents zoned to Grafton Middle School are zoned to Grafton High School. Grafton High School