...Introduction Chlorite is a general name for a group of magnesium rich hydrous sheet silicates possessing similar structure and chemical composition. Many green rocks owe their color to chlorite and chlorite owes its name to its green color. The Greek word choros, meaning “green,” is the origin of chlorite’s name. Consisting of negatively charged mica-like (2:1) layers regularly alternating with positively charged brucite-like (octahedral) sheets, the basic structure of chlorites allows for various compositions(Grim,1962). Members are differentiated by substitutions within the octahedral layer and the tetrahedral or octahedral positions of the mica-like layer. The arrangement of hydroxide and 2:1 sheets stacked in the z-direction defines the polytype of chlorite. There are theoretically six possible layer interlayer assemblages in either semi-random or regular "one-layer" polytypes. Of these six polytypes, four have been observed in nature (Partice De Caritat ect. 1993): clinochlore (Mg,Fe2+)5Al(AlSi3O10)(OH)8, chamosite (Fe2+,Mg)5Al(AlSi3O10)(OH)8, nimite (Ni,Mg,Al)6((Si,Al)4O10)(OH)8, and pennanite Mn52+Al(AlSi3O10)(OH)8. Provenance Chlorite is widespread throughout the world, often found in low- to medium-grade regional metamorphic rocks and as a secondary mineral to mafic silicates in igneous, metamorphic, and sedimentary rocks. It is an occasional constituent of igneous rocks, in most cases probably forming secondarily by deuteric or hydrothermal alteration of primary...
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...1 The analysis of Graphene material Alinur Mirassov, Azat Yerkinova, Gaukhar Balbayeva Madi Aldabergenov, Takhmina Torgayeva Abstract: Recently, graphene has attracted the interest of significant number of scientists and physicians due to its exceptional properties (e.g., large surface area, thermal and chemical stability, high conductivity). This new member of the carbon family has potential to revolutionize the current applications (some of them are described in the essay) as well as creating new set of applications. In this paper, we review the background of the novel material, its comprehensive atomic structure and properties that has fascinated the scientific community since its discovery. We also cover the synthesis of the material, including different effective methods that was investigated from the year of discovery until the present day. Finally, we discuss possible challenges and future perspectives in this rapidly enhancing scientific area. Key words: Graphene; Graphene-based material; 2-dimensional (2D); monolayer; Carbon nanotubes; Dirac level; fullerene; nanostructure; graphene synthesis; graphene applications. Reference to this paper should be made as follows: Aldabergenov, M., Balbayeva, G., Mirassov, A., Yerkinova, A. & Torgayeva, T. (2013) ‘The analysis of Graphene Material’, Astana: Nazarbayev University. 1 Introduction With the time movement and generation flow, the science and engineering achievements expands and widens by...
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...What is atomic number and atomic mass? 2. What are isotopes? 3. Explain the two models of the atom: Bohr atomic model and wave-mechanical model 4. What are the four quantum numbers? 5. Know how to write electron configurations for the first 20 elements in the periodic table. 6. What are the valence electrons? 7. Define electronegativity. How does it vary across a period and down a group? 8. Know the concept of bond forces and energies. Know the equations. 9. Define ionic, covalent, and metallic bonding. 10. What are secondary or van der Walls bonding? Chapter 3: 1. What is a crystalline solid? Are metallic solids crystalline? 2. What is a unit cell? Draw unit cells for FCC, BCC, HCP. 3. Know the properties of the crystal structures for the FCC, BCC, HCP. How many atoms per unit cell, relationship between edge length (a) and atomic radius (R), the APF, etc. 4. Know how to make density computations. 5. Know the crystallographic directions and planes. Know how to draw directions and construct planes. Know how to determine indices for the direction and Miller indices for the plane. 6. Study X-ray diffraction. Know how to solve problems similar to HW and similar to the ones solved in class. Chapter 4: 1. Point defects: Vacancies and self-interstitials 2. Calculate the equilibrium number of vacancies for a given material. 3. What is an alloy? What is a solid solution? How are solid solutions formed? 4. Define substitutional and interstitial solid solutions...
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...CRYSTAL STRUCTURES CRYSTAL STRUCTURES • Have you ever wondered how atoms assemble into solid structures? • How does the density of a material depend on its structures? CRYSTAL STRUCTURES • Solid materials can broadly be classified as crystalline and non crystalline (amorphous) solids. • In crystalline solid the arrangement of atoms is in a periodically repeating manner whereas no such patterns are found in a non-crystalline solid. CRYSTAL STRUCTURES • 2 types of crystalline solids: a) Single crystal : the periodic and repeated arrangement of atoms is perfect or extends throughout the entirety of the specimen without interruption. b) Polycrystalline solid : a collective aggregate of many crystals separated by well defined boundaries. CRYSTAL STRUCTURES • As a general rule, most metals are crystalline, while ceramics and polymers may be either crystalline or non-crystalline. Differences between crystalline and non-crystalline solids Characteristic Atomic arrangements Crystalline Regular and orderly manner in all three dimensions Non-crystalline Irregular Fracture mechanism Ductile manner. Solids Brittle manner. behave elastically up to Solids do not their yield points behave elastically Tensile strength Dislocation defects High Possible Low Not possible Unit cell • A crystalline solid consists of a number of crystals. A crystal structure can be considered as consisting of tiny blocks which are repeated in three dimensional pattern...
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...Solidification and crystalline imperfections: When molten alloys are cast, solidification starts at the walls of the mold as it is being cooled. The solidification of the alloy takes place not at a specific temperature but over a range of temperatures. While the alloy in the this range, it has a pasty form that consist of solid, tree-like structures called dendrites (meaning tree-like) and metal. The formation of Stable Nuclei in Liquid Metals: The two main mechanism by which the nucleation of solid particles in liquid metal occurs are homogeneous nucleation and heterogeneous nucleation. Homogeneous Nucleation in a liquid melt occurs when the metal itself provides the atoms needed to form nuclei. When a pre liquid metal is cooled below its equilibrium freezing temperature to a sufficient degree, many homogeneous nuclei are created by slow-moving atoms bonding together. For a nucleus to be stable so that it can grow into a crystal, it must reach a critical size. A cluster of atoms bonded together that is less than a critical size is called an embryo and one that is larger than the critical size is called a nucleus. Embryos: Small particles of a new phase formed by a phase (i. e. solidification) that are not of critical size and that can resolve. Nucle: Small particles of a new phase formed by a phase change (e . i . solidification) that can grow until the phase change is complete. Homogeneous Nucleation: The formation of small regions of a...
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...Crystal Structures The regular geometric shapes of crystals reflect the orderly arrangement of the atoms, ions, or molecules that make up the crystal lattice. Many different types of compounds will form crystals when solid; metals and ionic compounds are almost always in solid crystal form at room temperature. Only a few covalently bonded compounds are solids at room temperature. Of those covalent compounds that are solid, not all form crystals. The ones that do not are referred to as amorphous. Many covalently bonded compounds which are liquids or gases at room temperature will crystallize at lower temperatures (i.e. water forming ice). In this experiment, you will be using styrofoam spheres as models of atoms or ions to gain insight into the ways in which metallic or ionic crystals are formed. You will investigate three basic crystal structures which can form if all of the particles are the same size, as would happen in a pure metal: simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC). structures. Using the styrofoam models, you will determine the number of nearest neighbors (the coordination number) of the particles in each of these structures. In a simple crystal structure, all atoms or ions of the same type should have the same coordination number; in other words, any atom or ion of the same element is identical with respect to size and position relative to its neighbors. When ions form crystals, the cations and anions are...
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...Introduction to Polymer Reaction Engineering Part 1: Basic Concepts 1 2 Outline What is a polymer? •Nomenclature Polymer microstructure/properties •Chemical composition/sequence distribution •Molecular weight and distribution •Polymer architecture •Chain configuration •Morphology •Mechanical properties •Rheological properties •Glass transition temperature •Polymer modification/processing/additives 3 Outline Polymer classification •Step vs. Chain Growth Polymerization techniques •Bulk •Solution •Suspension •Emulsion •Gas-phase •Slurry Applications – Main commercial polymers •Polyolefins •Styrenic polymers •PVC •Waterborne dispersed polymers •Polyesters and polyamides •Thermosets Polymer history/timeline CHG 8187 Introduction to Polymer Reaction Engineering Part 1: Basic Concepts What is a polymer? 4 5 What is a polymer? Polymers are large molecular chains made of many monomers. Several structural units bound together by covalent bonds. 6 What is a polymer? 7 Nomenclature 1. Conventional: prefix “poly” followed by monomer name (e.g., poly(styrene), poly(methyl methacrylate)); condensation polymers from two monomers use name of repeat unit (e.g., poly(ethylene terephthalate). 8 Nomenclature 2. IUPAC* structure-based: similar to conventional but more powerful and general see text by Odian note also rules for copolymers. 3. Trade names (e.g., nylon, Kevlar, plexiglas, teflon, dacron, neoprene...
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...following groups contains only covalent molecular substances. (a) KOH; NH3; CO2 ; NH4Cl (b) NH4Cl; Cl2; H2S; H2SO4 (c) HNO3; H2SO4; SO2; Na2O (d) H2O; H2S; NH3; CH4 4. The physical properties of solid metals can best be explained proposing that: (a) each metal atom is bonded in the crystal lattice by covalent bonds. (b) positive metal ions are arranged in an orderly way, with valence electrons free to move through the crystal lattice. (c) positive and negative metal ions are arranged in an orderly way, with mobile valence electrons able to immigrate easily around the crystal lattice. (d) each metal atom is surrounded by a variable number of valence electrons, which complete a ‘noble gas’ electronic structure in the crystal lattice. 5. Which of these is not a characteristic of most ionic compounds? (a) It is a solid at room temperature. (b) It has a low melting point. (c) When melted it conducts an electric current. (d) It is composed of metallic and non-metallic elements. 6. A single covalent bond is: (a) not electrostatic in character. (b) the force between two oppositely charged ions. (c) the force between two atoms through the sharing of a pair of electrons. (d) the force between two atoms through the sharing of two pairs of electrons. 7. A major difference between ionic and covalent molecular compounds is that, in...
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...tetragonal lysozyme crystals H = Hexagonal lysozyme crystals X = Blank well P = precipitate ( M = medium crystals L = large crystals S = small crystals ) Incubated at 20 degrees Celsius | 1 | 2 | 3 | 4 | 5 | 6 | ROW A | T (a few) M | P | X | T (a lot) M | P | X | ROW B | X | P | H (a few) M | X | P | H (a lot) M | ROW C | T (a few) L | P | X | T (a lot) L | P | X | ROW D | X | P | H ( a few) L | X | P | H (a lot) L | Incubated at 4 degrees Celsius | 1 | 2 | 3 | 4 | 5 | 6 | ROW A | T (a few) S | P | X | T (a lot) S | P | X | ROW B | X | P | H (a few) S | X | P | H (a lot) S | ROW C | T(a few) S | P | X | T (a lot)S | P | X | ROW D | X | P | H (a few) S | X | P | H (a lot) S | 1: The best condition for tetragonal lysozyme crystal formation is Row C in the 5% to 7% NaCL at pH 4.5 (60mg/ml) large crystals 2: The best condition for hexagonal lysozyme crystal formation is Row D in the 2% to 3% NaNO3 at pH 7.5 (60mg/ml) large crystals 3: Tetragonal lysozyme crystals are primarily found in the NaCL solution 4: Hexagonal lysozyme crystals are primarily found in the NaNO3 solution 5: Temperature proved to have a substantial effect on crystal size as all the crystals formed while incubated at 4 degrees Celsius were small crystals. 1HEW Crystal structure. Experiment...
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...Written Assignment 1: Intermolecular Forces and Liquids and Solids Answer all assigned questions and problems, and show all work. 1. Explain and give an example for each type of intermolecular force. A: a. Dipole-dipole interaction: a dipole-dipole interaction is the electrostatic attraction between the positive end of one polar molecule and the negative end of the other. Dipole-dipole attraction occurs between molecules which are permanent dipoles (polar covalent molecules). An example of a dipole-dipole interaction is HCl and HCl. b. Dipole-induced dipole interaction: a dipole-induced dipole interaction is produced in neutral molecules when they are introduced into a magnetic field (i.e induced by an electric current or by a permanent dipole). Subjecting a neutral molecule to such magnetic fields has effects on the charge of the molecule. The negative charges concentrate in a specific point totally opposite from the positive charges. An example of dipole-induced dipole interaction is HCl and H2 c. Ion-dipole interaction: an ion-dipole interaction is the force between an ion and a neutral polar molecule which possess a dipole moment. Polar molecules are dipoles; they have a positive end and a negative end. The positive ions are attracted to the negative end of a dipole, while negative ions are attracted to the positive end. An example of ion-dipole interaction is K+ ---H2O d. Dispersion forces (London forces): London forces are weak intermolecular...
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...Lecture 1 Introduction to Semiconductor Devices Reading: Notes and Anderson2 Chapters 1.1-1.3, 1.7-1.9 Georgia Tech ECE 3080 - Dr. Alan Doolittle Atoms to Operational Amplifiers •The goal of this course is to teach the fundamentals of non-linear circuit elements including diodes, LEDs, LASER diodes, transistors (BJT and FET) , and advanced device concepts such as microwave compound semiconductors and state of the art devices. •Due to the diverse coverage from various professors for ECE3040, you will repeat (for some) some of the material from 3040. Specifically, you will learn about the fundamentals of electron movement in semiconductor materials and develop this basic knowledge of how we can construct devices from these materials that can control the flow of electrons and light in useful ways. Georgia Tech ECE 3080 - Dr. Alan Doolittle Market Study Silicon is and will for a very long time be the dominant material used for electronics. However, MANY up and coming materials are slowly eating into silicon’s dominance. Compound semiconductors Compound semiconductors Organic and compound semiconductors Georgia Tech ECE 3080 - Dr. Alan Doolittle Devices we will study Bold indicates devices covered in depth in ECE 3040 P-N diode, heterojunction diodes, ballistic diodes, Schottky barrier diodes, Metal-Semiconductor Contacts, LEDs, Lasers, Solar Cells, Photodetectors, BJT, HBT, MOSFET, MESFET, JFET, Polarization Based Devices (III-Nitrides HEMTs...
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...article is about how external environment affects the molecular structure of water (shown as crystal formation) – the controversial experiment was conducted by Dr. Masaru Emoto. He published these results as photograph collections: “Messages from Water 1” (1999), “Messages from Water 2” (2002), “Messages from Water 3” (2004), and “Messages from Water 4” (2008).(Retrieved from http://masaru-emoto.net/english/ephoto.html). Rebuttal Article: “Hidden Messages in Water” Dr. Masaru Emoto is very well-known of his experimentation about water crystal formation. He claims that external environment and human consciousness affect the molecular structure of water as shown in crystal formation. According to him, “We start out life being 99% water, as fetuses. When we are born, we are 90% water, and by the time we reach adulthood we are down to 70%. If we die of old age, we will probably be about 50% water. In other words, throughout our lives we exist mostly as water. From a physical perspective, humans are water. When I realized this and started to look at the world from this perspective, I began to see things in a whole new way.” (Emoto 2004) Studies behind Hidden Messages in Water Dr. Masaru Emoto started his studies of molecular structure of water by freezing and looking at the crystal. He used different kind of water: tap, natural and...
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...Crystal Structure of Lymnaea stagnalis AChBP Complexed with the Potent nAChR Antagonist DHb E Suggests a Unique Mode of Antagonism Azadeh Shahsavar1, Jette S. Kastrup1, Elsebet Ø. Nielsen2, Jesper L. Kristensen1, Michael Gajhede1, Thomas Balle1*¤ 1 Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark, 2 NeuroSearch A/S, Ballerup, Denmark Abstract Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels that belong to the Cys-loop receptor superfamily. These receptors are allosteric proteins that exist in different conformational states, including resting (closed), activated (open), and desensitized (closed) states. The acetylcholine binding protein (AChBP) is a structural homologue of the extracellular ligand-binding domain of nAChRs. In previous studies, the degree of the C-loop radial extension of AChBP has been assigned to different conformational states of nAChRs. It has been suggested that a closed C-loop is preferred for the active conformation of nAChRs in complex with agonists whereas an open C-loop reflects an antagonist-bound (closed) state. In this work, we have determined the crystal structure of AChBP from the water snail Lymnaea stagnalis (Ls) in complex with dihydro-b-erythroidine (DHbE), which is a potent competitive antagonist of nAChRs. The structure reveals that binding of DHbE to AChBP imposes closure of the C-loop as agonists, but also a shift perpendicular...
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...Pure chemical substances are classified as ionic, metallic, covalent molecular and covalent network. In this essay I will describe the nature of each bonding present in these different types of substances and use this to explain the physical properties they exhibit and their structures. Ionic compounds are compounds that are composed of positive and negative ions. An ionic compound is a chemical compound in which ions are held together in a lattice structure by ionic bonds. Usually, the positively charged portion consists of metal (cations) and the negatively charged portion is an (anion) or polyatomic ion. Ions in ionic compounds are held together by the electrostatic forces between oppositely charged bodies. The positive and negative ions in these compounds are thought to be arranged in an orderly three-dimensional lattice. For example, the structure of sodium chloride is shown. In the lattice, each positive sodium ion is surrounded by six negative chloride ions and each negative chloride ion is surrounded by six positive sodium ions. The position of the ions is fixed and apart from vibration about these fixed positions no other movement of the ions occurs in the solid compound. Each ion in an ionic solid is held in the crystal lattice by strong electrostatic attractions to the oppositely charged ions around it. These electrostatic forces between the positive and negative ions are called ionic bonds. Because ionic compounds have high melting points, in other words considerable...
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...SCH 4U0 TEST - Structures NAME _________________ March 30, 2011 Multiple Choice: Choose the most correct answer to the following questions and circle the letter of your choice. (10 marks) 1. A compound is formed of white crystals that melt at 1205oC to form a liquid that conducts electricity. The crystals being described are most likely: (A) molecular (B) metallic (C) ionic (D) dipole (E) covalent network 2. Which of the following will display the most noticeable effects due to hydrogen bonding? (A) H20 (B) B2H6 (C) CH4 (D) HI (E) PH3 3. The scientist that proposed the "raisin bun" model of the atom was: (A) Thomson (B) Rutherford (C) Bohr (D) Chadwick (E) Einstein 4. The total maximum number of electrons possible in the fourth energy level is: (A) 8 (D) 18 (C) 36 (D) 50 (E) none of these 5. The correct electron configuration for the valence shell of tin is: (A) 5s25p2 (B) 5s25d2 (C) 5s25p25d10 (D) 5s24d105p2 (E) none of these 6. Which of the following best represents the most likely value for the bond angle for the H2CO molecule? (A) 180º (B) 120º (C) 118º (D) 109.5º (E) 104.5º 7. Which one of the following are groups of isoelectronic particles? (A) K+, Cl-, S2- (B) F-, Cl-, Br- (C) K-, Ca2+, S2- (D) K+, Ar, Cl+ (E) K, Ar, Cl 8. Rutherford’s famous gold-foil experiment led to the...
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