Wikipedia:Articles for creation/2007-06-24

Chris Aable

Chris Aable was born in Bossier City, Louisiana and moved to Los Angeles in 1986. Chris Aable is famous for his interviews with hundreds of celebrities, such as Bruce Vilanch, Gedde Watanabe and Gilbert Gottfried. His interviews with Gottfried can be viewed on YouTube and MySpace. Chris Aable hosted the TV Show "Hollywood Today" in the 1990s. Chris Aable has been interviewed by Reginald Vaughn Finley, Sr.. Finley is also known as "The Infidel Guy". As such, Aable was one of the first psychologist discuss the nature of belief and non-belief in god or gods on the show.
Chris Aable taught Psychology and Sociology at CSULA and Santa Monica College

Sources

http://www.self-evolution.org/
http://www.self-evolution.org/celebrities.htm
http://www.self-evolution.org/documentation.htm
http://www.myspace.com/aable
http://www.syrradio.com/
http://www.youtube.com/watch?v=h-QjVfNvKp4
http://www.lastfm.co.kr/music/The+Infidel+Guy/_/Tape157+Chris+Aable+Self
http://en.wikipedia.org/wiki/The_Gong_Show
http://en.wikipedia.org/wiki/Rock_Hudson
http://www.self-evolution.org/Tape157_Chris_Aable_Self_Evolution.mp3

68.183.150.209 00:16, 24 June 2007 (UTC)[reply]

shes fit x

Sources

80.7.172.122 00:52, 24 June 2007 (UTC)[reply]

Matt Walker

Matt "Mestizo Matt" Walker was born on june 27, 1990 in Tucson, AZ. He now resides in Arlington, TX, where he currently attends Summit High School. Walker is a half Mexican/half American hybrid, earning him the nickname "Mestizo Matt". Walker is one of the main teenage contributor to the gay rights movement. He has lead several homosexual rallies at his local high school.

Walker dons the mohawk, quickly becoming the symbol for the homosexual community. Recently, Walker became a member of Queer Nation and was one of the main contributors to the slogan: "We're here. We're Queer. Get used to it.".

Sources

[[1]] [Matt on Myspace] [[2]] [[3]] [[4]] 76.183.141.230 00:58, 24 June 2007 (UTC)[reply]

Cerro Azul, Panama

Cerro Azul is located just 45 minutes from Panama City and 20 minutes from Tocumen International Airport.

Cerro Azul is a hilly area with a nice temperature range from 60 to 75° F, cool mountain breeze and low clouds. Lush vegetation, exotic birds and the very unique wildlife of a tropical rainforest dominate Cerro Azul.

A well paved road takes you to Cerro Azul where you can find some restaurants, a couple of hotels and cabins, and a beautiful lake. There is access to water, electricity and telephone services.

Cerro Azul is the perfect place to relax: privacy in a tropical forest near the city's more modern scene.

Sources

http://www.escapeartist.com/efam/57/Cerro_Azul_Panama.html http://www.panamatravelers.com/12/the-high-hills-of-the-chagres-national-park/#more-12 201.218.93.35 01:43, 24 June 2007 (UTC)[reply]

Genevieve Anne Bentz

Genevieve Anne Bentz is a young, emerging, artist in the Stonington, Connecticut area. Her artistic training is relatively minimal: only minor training and some direction from Connecticut College professor Martha Wakeman.

Her most effective mediums are acrylic, pastel, and photography. Although her pastels are more famous, she has also won national recognition for her waterfowl acrylics. Her most recent acrylic, a female bufflehead duck, won best in show in the 2006 Connecticut Jr. National Duck Stamp Competition sponsored by the US Fish and Wildlife Service.

She started painting at the age of seven and has now earned renown for her abstract skys as well as smaller landscape portraits.

Sources

http://www.fws.gov/duckstamps/junior/JDprogram/Connecticut.htm

http://www.marthawakeman.com/index.php/studyretreats/category/section/Faculty/

http://www.answers.com/topic/genevieve-bentz

64.252.3.57 02:24, 24 June 2007 (UTC)[reply]

Shane Randig

Shane Randig is a gay fag.

Sources

http://picasaweb.google.com/hendricksonsoccer/HHSBoysSoccer2007Varios/photo#5024194644367690098

71.155.190.108 02:26, 24 June 2007 (UTC)[reply]

Geopolymer

Introduction

Geopolymers, a term first coined by Joseph Davidovits in 1978, (citation needed) covers a class of aluminosilicate materials polymerised by reaction with alkaline silicate solution at roughly ambient conditions. Some of the drive behind research is to investigate the development of geopolymers as a potential large-scale replacement for concrete produced from Portland Cement. This is due to the geopolymers’ lower carbon dioxide emissions, greater chemical and thermal resistance and greater mechanical properties at both atmospheric and extreme conditions .

Metakaolin is a commonly used starting material in present work synthesising geopolymers . It is calcined kaolinite clay and has the standard formula of 2SiO₂•Al₂O₃. Geopolymers can also be made from natural sources of pozzolanic materials, such as lava or fly ash (coal combustion product). Most geopolymeric studies have been carried out using natural or industrial waste sources of metakaolin and other aluminosilicates. By mixing it with a solution mixture of potassium hydroxide and silica the geopolymerisation reaction is completed before curing.

Theory

The majority of Earth’s crust is made up of Si-Al compounds. Davidovits proposed in 1978 that a single aluminium and silicon-containing compound, most likely geological in origin, could react in a polymerisation process with an alkaline solution. The binders created were termed “geopolymers”, although now, the majority of aluminosilcate sources are by-products from organic combustion, like fly ash from coal combustion. These inorganic polymers have a chemical composition somewhat similar to zeolitic materials, however exist as an amorphous solid, rather than having a crystalline microstructure.

Structure

The chemical reaction that takes place to form geopolymers is believed to occur as such (Xu and Van Deventer, 2000);

• Dissolution of Si and Al atoms from the source material due to hydroxide ions in solution;

• orientation of precursor ions into monomers, and;

• setting via polycondensation reactions into an inorganic polymer.

Once formed, these geopolymers are categorised by one of three forms, related to their backbone connectivity (Davidovits, 1999):

• Poly-sialate -(-Si-O-Al-O-)-

• Poly-sialate-siloxo -(-Si-O-Al-O-Si-O-)-

• Poly-sialate-disoloxo -(-Si-O-Al-O-Si-O-Si-O-)-

In each chain, each Al and Si atom is bound to two more oxygen atoms not part of the backbone. This particular model, while neat, has a number of shortcomings. Firstly, it implies that only integer ratios can exist between Si and Al ,8. This is not true, as compositions can be made for a wide and continuous range of ratios. These ratios can be accounted for by combinations of the above monomers that would result in the actual existing formula within a mixture, not necessarily restricted to one of the above compositions. Secondly, it implies that geopolymers are analogous to organic polymer and exist in discrete chains. Geopolymers are in fact 3-dimensional networks of aluminosilicates that form around Si and Al atoms interconnected by oxygen, as opposed to 1-dimensional chains that are shown above. For this reason, even the name geopolymer is misleading to an extent and has even been used to describe compounds outside the discussed range (Provis, 2005)^iv,v .

Sources and Production

The solids often used for geopolymer production include the minerals kaolinite and metakolin. Kaolinite is a layered clay mineral, fairly soft and usually white with a composition of Al₂Si₂O₅(OH)₄, while metakaolin is simply a dehydroxylated version of the same (usually via furnace calcination). These are relatively inexpensive compared to some of the other powders that can be used, hence their widespread usage. However they are not as cheap as, and still used as a secondary source of soluble aluminosilicate compared to, natural or waste aluminosilicate materials like fly ash. If the Al atoms do not dissolve quickly enough, which is known to happen from the less pure sources, addition of the purer minerals is necessary, although being quite soft minerals, these form weaker structures than the alternative sources. The variables associated with sourcing naturally occurring minerals and waste products that contain aluminosilicate means this is not completely understood, but could be somewhat addressed by negating the contaminants and preset mineral structures through synthetically deriving the aluminosilicate in a pure and homogenous solution .

While producing a purer form of aluminosilicate will remove some uncertainty, it also reduces excess other compounds and aggregates that provide a form of support in the matrix of the gel phase during the geopolymerisation. It also means there is going to be excessive water present during the process since all the precursors have come from pure solutions or suspensions. Excess water is then also added during the final reaction step to assist with dispersion and wetting of the high surface area. This is both a concern for waste, if it is to be scaled for mass production, and since excess water in the polymerisation step is known to reduce the compressive strength and will also created shrinkage and cracking in the final cured product. Any cracking is detrimental to a material’s strength, and in searching for a high-strength, high thermal and chemical resistant material, this cracking and shrinkage could be catastrophic.

Metakaolin as a natural source is often not completely reacted and dissolved in the alkaline solution. This is not understood to be a completely negative outcome, since the remaining material as unreacted metakaolin sheets can provide intra-matrix support and can be related to the relative surface area of particles. However, Gordon et al. found the microstructure of the synthetically-derived geopolymer was denser than natural versions, and appeared to be due to a higher surface area, which lead to a greater extent of dissolution and reaction. Natural metakaolin would approach this state the more it was milled. Wang et al. stated that more milling resulted in less sheets of unreacted metakaolin remaining and a denser final geopolymer. Since the surface area of synthetic metakaolin is magnitudes larger than natural versions, it is easy to accept that synthetic versions would completely dissolve, react and form denser productsⁱⁱ.

Since geopolymers cure at just above ambient temperatures normallyⁱⁱ, the accelerated reaction of synthetic metakaolin with alkaline solutions due to greater surface area and less impurities present would indicate some need to cool the mixture to slow the reaction. If not, the reaction could commence curing before mixing is complete, creating lumps of hard geopolymer, as opposed to a homogenous paste or gel. By placing in an ice bath it is hoped to allow more complete dissolving and mixing before individual clumps that happen to contact solution first might harden. It is this idea that will determine a “workable” geopolymer mixture – whether the mixing of aluminosilicate powder with alkaline silicate solution produces a paste that mixes homogeneously before setting; that syringe samples can be taken from the bulk while still fluid with some ease, and; that the resulting cured geopolymer still retains integrity through minimal cracking and shrinkage.

While the most common alkaline solution used in geopolymer production is a sodium hydroxide / sodium silicate mixture (NaOH / Na₂SiO₃) since it dissolves the Al-Si to a higher extent, other alkaline-silicate solutions are available. Xu and Van Deventer found in 1999 that KOH and K₂SiO₃ actually produced a stronger compound. However, by synthesising the mineral precursors from pure compounds, not naturally contaminated sources, the surface area and extent of reaction is greatly increased, which could go someway to redeeming potassium’s size disadvantage due to ion-pair theory^iv. By coupling the stronger potassium-based alkaline solution with the more extensive reactions of synthetic metakaolin a fast-reacting, fully converted geopolymer could be produced.

It has also been shown from experimental methods that sodium silicate solutions have difficulties with stability, particularly the low silicate solutions, and crash out on a short time scale. Potassium hydroxide solutions also have a lower viscosity and level of adhesion than sodium alternatives, making it easier to mix with the powders. The solutions of KOH/SiO2 in the lab did not show any crystallisation across any of the concentration ratios, as opposed to the NaOH/SiO2 versions, which had much greater collection of solid around the bottom of their containers and the rims.

From Xu and van Deventer (2000), a positive correlation between geopolymeric compressive strength and factors such as the molar Si/Al ratio, % K₂O, the use of KOH as alkali and % CaO in the material was identified. These factors were all included within this project’s scope to determine a methodology for producing geopolymers with a range of these factors for future testing of their correlation to the proposed theory. This study however, has a limited usefulness in directly considering and applying factors as it took multiple variables and assumed a direct, linear correlation to all of them simultaneously. Considering independent research indicates that an optimal mechanical strength is actually provided by a moderate Si/Al ratioⁱ, and not a maximum or minimum, this linear relationship would not hold and it could be assumed that this may be the case for other factors too. The overall work done on characterising different factors within the geopolymer field has been useful in identifying certain extents of correlations, such as difference between KOH and NaOH^vi.

The addition of calcium into the powder also has some interesting and promising discoveries. Calcium compounds are the major components in Ordinary Portland Cement and also in zeolites. Geopolymers are specifically alkaline-activated aluminosilicate compounds, but the strength and other properties calcium could provide is a common feature of geopolymer study. This is especially important since most of the natural sources of aluminosilicate for geopolymer contains calcium as the next most abundant and compositionally significant element. Yip and van Deventer (2003) found that the presence of calcium within these mixtures often resulted in a second phase of calcium silicate hydrate (CSH) within the final geopolymer. This is a gel of non-stoichiometric CaO-SiO₂ and is a major component for mechanical strength within cement. Their report found that after metakaolin was reacted with alkaline in the presence of ground granulated blast furnace slag the two phases were formed; one consisting of mostly aluminium and silicon with the alkaline cation and only 1 mol% of calcium, and; the second phase consisting of silicon and calcium with less than 3 mol% aluminium. This is indicative of a phase of geopolymer and a phase of CSH coexisting in the overall compound. Trying to simulate the second phase by adding a source of calcium to the synthetic aluminosilicate powder could go some way to understanding the difference that the calcium actually makes to the composition of Ca-containing geopolymeric materials .

References

(i) Duxson, P, Provis, JL, Lukey, GC, Mallicoat, SW, Kriven, WM, van Deventer, JSJ; 2005; Understanding the relationship between geopolymer composition, microstructure and mechanical properties; Colloids and Surfaces A: Physicochem. Eng. Aspects, 269, 47-58

(ii) Wang, H, Li, H, Yan, F; 2005; Synthesis and mechanical properties of metakaolinite-based geopolymer; Colloids and Surfaces A: Physicochem. Eng. Aspects, 268, 1-6

(iii) Fletcher, RA, MacKenzie, KJD, Nicholson, CL, Shimada, S; 2005; The composition range of aluminosilicate geopolymers; J. European Ceramic Society, 25, 1471-1477

(iv) Provis, JL; 2006; Modelling the formation of geopolymers; Dept of Chemical and Biomolecular Eng., University of Melbourne

(v) Provis, JL, Lukey, GC, van Deventer, JSJ; 2005; Do Geopolymers actually contain nanocrystalline zeolites? A re-examination of existing results; Chem Mater, 17, 3075-3085

(vi) Xu, H, van Deventer, JSJ; 1999, The geopolymerisation of alumino-silicate minerals; Int. J. Mineral Processing, 59, 247-266

(vii) Rahier, H, Denayer, JF, van Mele, B; 2003; Low Temperature synthesized aluminosilicate glasses; J. Materials Science, 38, 3131-3136

(viii) Provis, JL, Sarin, P, Gordon, M, Bell, JL, van Deventer, JSJ, Kriven, WM; 2006; Atomic Structure and thermal transformation of a cesium aluminosilicate geopolymer; A pair distribution function study; Dept of Chem. And Biomolec. Eng. Unimelb & Dept. Mater. Sci and Eng, The University of Illinois, Urbana-Champaign

(ix) Yip, CK, van Deventer, JSJ; 2003; Microanalysis of calcium silicate hydrate gel formed within a geopolymeric binder; J. Materials Science, 38, 3851-3860

The audacious art experiment is a UK record label based in Sheffield, Grimsby, London and Leeds in the UK. It is a collaboration between friends aiming to release records from the UK Punk and hardcore music scene. The label cites that it's aim is to release original music that has not been heard before, is unique or has a message to say. The label thusfar has 10 release including the rise which features members of and you will know us by the trail of the dead