Did You Know about XML?

The XML was designed to describe data and focus what data is
It also stands for Extensible Markup Language. The markup language much like HTML but it just that the tags are not predefined like the HTML. The purpose of designed oh XML is to provide simplicity, generality and usability over the internet.

The XML uses a DTD or an XML schema to describe the data
as with a DTD or XML Schema is designed to self-descriptive


The differences between XML and HTML :

XML	HTML
Transport data	Display data
Focus on the data	Focus on the looks of data
Carrying the information	Display and convert into information

XML was created to structure, store, and transport information. XML is nothing special it is just plain text. Therefore software that can handle plain text can also handle XML. However, XML-aware applications can handle the XML tags specially.

The functional meaning of the tags depends on the nature of the application

The important things is with XML You can invent your Own Tags because the tags is not predefined.

XML is Everywhere

We have been participating in XML development since its creation

It has been amazing to see how quickly the XML standard has developed, and how quickly a large number of software vendors have adopted the standard.

XML is now as important for the Web as HTML was to the foundation of the Web. It is now the most common tool for data transmissions between all sorts of applications, and is becoming more and more popular in the area of storing and describing information

XML Makes Your Data More Available

Since XML is independent of hardware, software and application, XML can make your data more available and useful. Different applications can access your data, not only in HTML pages, but also from XML data sources . With XML, your data can be available to all kinds of "reading machines" (Handheld computers, voice machines, news feeds, etc), and make it more available for blind people, or people with other disabilities

XML is used to Create New Internet Languages

A lot of new Internet languages are created with XML. Here are some examples:

• XHTML the latest version of HTML
• WSDL for describing available web services
• WAP and WML as markup languages for handheld devices
• RSS languages for news feeds
• RDF and OWL for describing resources and ontology
• SMIL for describing multimedia for the web

There are other sources of the info CLICK HERE
                                                        CLICK HERE

chemsketch

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What is ACD/ChemSketch?

ACD/ChemSketch is a chemical drawing software package from Advanced Chemistry.Development, Inc. designed to be used alone or integrated with other applications. ChemSketch is used to draw chemical structures, reactions and schematic diagrams. It can also be used to design chemistry-related reports and presentations.

ChemSketch’s features:

-Structure Mode

for drawing chemical structures and calculating their properties.

-Draw Mode

for text and graphics processing.

-Molecular Properties

-calculations for automatic estimation

·        - molecular weight

· ·       -  molar refractivity

·        - molar volume

·       -  parachor

·       -  index of refraction

·       -  surface tension

·       -  density

·       -  dielectric constant  and

 polarizability.

 
There also some shortcut that can be used in Chemsketch.The table below show some example of shortcut that can be use in Chemsketch :

 

Show Aromaticity	Keyboard: CTRL+SHIFT+A
Hide Aromaticity	Keyboard: CTRL+SHIFT+H

To know more about Chemsketch  click here.

About SMILES

Smiles

The simplified molecular input line entry system or smiles is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. Smiles strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules.

It is widely used all over the world and in many job scopes. The simplified way of using atomic symbols and a set of intuitive rules as well as hydrogen-suppressed molecular graphs is computationally efficient. SMILES is categorized into two: Canonical SMILES and Isomeric SMILES.

The term Canonical SMILES refers to the version of the SMILES specification that includes rules for ensuring that each distinct chemical molecule has a single unique SMILES representation. A common application of Canonical SMILES is for indexing and ensuring uniqueness of molecules in a database. Isomeric SMILES refers to the version of the SMILES specification that includes extensions to support the specification of isotopes, chirality, and configuration about double bonds. A notable feature of these rules is that they allow rigorous partial specification of chirality.

Graph-based definition 

                In terms of a graph-based computational procedure, SMILES is a string obtained by printing the symbol nodes encountered in a depth-first tree traversal of a chemical graph. The chemical graph is first trimmed to remove hydrogen atoms and cycles are broken to turn it into a spanning tree. Where cycles have been broken, numeric suffix labels are included to indicate the connected nodes. Parentheses are used to indicate points of branching on the tree. 

 

SMILES Branches

                It is represented by enclosure in parentheses. It also can be nested or stacked.                            

   For examples;

CC(O)CC is 2-Butanol

OCC(C)C iso-Butanol

OC(C)(C)C is tert-Butanol

 SMILES Symbols

·         String of alphanumeric characters and certain punctuation symbols.

·         Terminates at the first space encountered when read left to right.

·         The organic subset: B, C, N, O, P, S, F, Cl, Br, I

·         Aliphatic or nonaromatic ring: lowercase letter

·         Designate ring closure with pairs of matching digits, e.g.

c1ccccc1 is Benzene, whereas

C1CCCCC is Cyclohexane

 

SMILES Cyclic Structures

·         Break one single or one aromatic bond in each ring

·         Number in any order

                   –Designate ring-breaking atoms by the same digit following the atomic symbol.

·         Numbers indicate start and stop of ring

·         Same number indicates start and end of the ring, entered immediately following the start/end atoms

·         Only numbers 1 –9 are used

·         A number should appear only twice

·         Atom can be associated w. 2 consecutive numbers, e.g., Napthalene: c12ccccc1cccc2

SMILES Conventions

·         Avoid two consecutive left parentheses if possible

·         Strive for the fewest number of possible branches

·         Tautomeric bonds are not designated; enter the appropriate form

·         A branch cannot begin a SMILES notation

·         A branch cannot immediately follow a double-or triple-bond symbol

·         Example: C=(CC)C is invalid, but

·         C(=CC)C or C(CC)=C are valid SMILES

SMILES Cyclic Structures

·         Break one single or one aromatic bond in each ring

·         Number in any order

                   –Designate ring-breaking atoms by the same digit following the atomic symbol.

·         Numbers indicate start and stop of ring

·         Same number indicates start and end of the ring, entered immediately following the start/end atoms

·         Only numbers 1 –9 are used

·         A number should appear only twice

·         Atom can be associated w. 2 consecutive numbers, e.g., Napthalene: c12ccccc1cccc2

SMILES Conventions

·         Avoid two consecutive left parentheses if possible

·         Strive for the fewest number of possible branches

·         Tautomeric bonds are not designated; enter the appropriate form

·         A branch cannot begin a SMILES notation

·         A branch cannot immediately follow a double-or triple-bond symbol

·         Example: C=(CC)C is invalid, but

·         C(=CC)C or C(CC)=C are valid SMILES

SMILES Fragment(see table below):

Nitro	N(=O)(=O)
Sulfonic acid	S(=O)(=O)O
Cyanide/nitrile	C#N

Link to SMILES database here: Click Here