SUMMARY / RELATED TOPICS

Substrate (chemistry)

In chemistry, a substrate is the chemical species being observed in a chemical reaction, which reacts with a reagent to generate a product. It can refer to a surface on which other chemical reactions are performed, or play a supporting role in a variety of spectroscopic and microscopic techniques. In synthetic and organic chemistry, the substrate is the chemical of interest, being modified. In biochemistry, an enzyme substrate is the material upon; when referring to Le Chatelier's principle, the substrate is the reagent whose concentration is changed. The term substrate is context-dependent. In three of the most common nano-scale microscopy techniques, atomic force microscopy, scanning tunneling microscopy, transmission electron microscopy, a substrate is required for sample mounting. Substrates are thin and free of chemical features or defects. Silver, gold, or silicon wafers are used due to their ease of manufacturing and lack of interference in the microscopy data. Samples are deposited onto the substrate in fine layers where it can act as a solid support of reliable thickness and malleability.

Smoothness of the substrate is important for these types of microscopy because they are sensitive to small changes in sample height. Various other substrates are used in specific cases to accommodate a wide variety of samples. Thermally insulating substrates are required for AFM of graphite flakes for instance, conductive substrates are required for TEM. In some contexts, the word substrate can be used to refer to the sample itself, rather than the solid support it is placed on top of. Various spectroscopic techniques require samples to be mounted on substrates such as powder diffraction; this type of diffraction, which involves directing high-powdered X-rays at powder samples to deduce crystal structures is performed with an amorphous substrate such that it does not interfere with the resulting data collection. Silicon substrates are commonly used because of their cost-effective nature and little data interference in X-ray collection. Single crystal substrates are useful in powder diffraction because of they distinguishable from the sample of interest in diffraction patterns by differentiating by phase.

In atomic layer deposition, the substrate acts as an initial surface on which reagents can combine to build up chemical structures. A wide variety of substrates are used depending on the reaction of interest, but they bind the reagents with some affinity to allow sticking to the substrate; the substrate is washed in between to remove excess. A substrate is critical in this technique because the first layer needs a place to bind to such that it is not lost when exposed to the second or third set of reagents. In biochemistry, the substrate is a molecule upon. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate bonds with the enzyme active site, an enzyme-substrate complex is formed; the substrate is transformed into one or more products, which are released from the active site. The active site is free to accept another substrate molecule. In the case of more than one substrate, these may bind in a particular order to the active site, before reacting together to produce products.

A substrate is called'chromogenic' if it gives rise to a coloured product when acted on by an enzyme. In histological enzyme localization studies, the colored product of enzyme action can be viewed under a microscope, in thin sections of biological tissues. A substrate is called'fluorogenic' if it gives rise to a fluorescent product when acted on by an enzyme. For example, curd formation is a reaction. In this reaction, the substrate is a milk protein and the enzyme is rennin; the products are two polypeptides that have been formed by the cleavage of the larger peptide substrate. Another example is the chemical decomposition of hydrogen peroxide carried out by the enzyme catalase; as enzymes are catalysts, they are not changed by the reactions. The substrate, however, is/are converted to product. Here, hydrogen peroxide is converted to oxygen gas. E + S ↽ − − ⇀ ES ⟶ EP ↽ − − ⇀ E + P Where E is enzyme, S is substrate, P is productWhile the first and third steps are, in general, the middle step may be irreversible or reversible.

By increasing the substrate concentration, the rate of reaction will increase due to the likelihood that the number of enzyme-substrate complexes will increase. Although enzymes are highly specific, some are able to perform catalysis on more than one substrate, a property termed enzyme promiscuity. An enzyme may have many native substrates and broad specificity or it may have a single native substrate with a set of similar non-native substrates that it can catalyse at some lower rate; the substrates that a given enzyme may react with in vitro, in a laboratory setting, may not reflect the physiological, endogenous substrates of the enzyme's reactions in vivo

Sonoma Wire Works

Sonoma Wire Works is a company, based in Los Altos and incorporated in 2003, that develops audio software and hardware. Sonoma Wire Works began in an outbuilding in California. Three audio engineers, who worked in the audio industry for over 20 years combined, wanted to create an easy and fun recording application for guitarists; the result of their work was RiffWorks guitar recording software with built-in InstantDrummer, online collaboration, song posting, more. Hayden Bursk joined the development team after graduating from the Center for Computer Research in Music and Acoustics at Stanford University. RiffWorks development has continued with additional features being added, the launch of RiffWorks T4 free recording software, the new RiffWorld.com online community for RiffWorks users. Nine employees now work at Sonoma Wire Works. In 2004, Sonoma Wire Works launched their first product, RiffWorks recording software for Mac and Windows, designed for use by guitar players. Over the next few years, RiffLink online music collaboration was built into RiffWorks, song posting to Sonoma Wire Works' RiffWorld.com online community was added.

In addition, over 100 RiffWorks InstantDrummer Sessions were launched. In 2008, Sonoma Wire Works become an iOS application development company with the launch of the FourTrack multitrack recorder for musicians who want to capture musical ideas and record songs on their iPhone. In 2009, Sonoma Wire Works acquired software and drum content from Submersible Music and Discrete Drums, including DrumCore, a plug-in drum instrument with stereo audio loops and MIDI recordings of well-known drummers. In 2010, Sonoma Wire Works developed the StudioTrack audio recorder for the iPad, the GuitarJack audio interface for FourTrack, StudioTrack, GuitarTone, other compatible iOS apps. Create Digital Music - Music Player Live Reviewed.

Cristina Rodríguez Cabral

Cristina Rodríguez Cabral is an Uruguayan poet and Afro-Uruguayan activist. Rodríguez has a degree in sociology and nursing, a profession that she practiced for some time in Uruguay, he continued her academic training at the University of Missouri, where she obtained her PhD. She resides in the United States of America, where she works as a researcher and university professor. Rodríguez took an interest in literature at 11 years of age, her first publications were published by the organization Mundo Afro, which campaigned for the equal rights of African diaspora in Uruguayan. In 1986, her work Bahía, mágica Bahía won the Casa de las Américas Prize. Rodríguez Cabral is an international reference in Afro-Uruguayan literature, one of the few living afro-descendant writers to whom academic studies have been dedicated. In general, Rodríguez's work deals with marginalization and oppression on the grounds of race and gender. There is, in her works, "a need to remember and reaffirm the inherited values of both our family and Africa."

Her initial works are focused on her feelings and intimate experiences from the perspective of a black Hispanic-American woman. In her post-1995 works, she introduces themes related to social militancy and cultural identity