![Conformations of [beta]-amino acid residues in peptides: X](http://s1.studyres.com/store/data/003974629_1-521aa7943d558a5d58755964c90b9e45-300x300.png)
Conformations of [beta]-amino acid residues in peptides: X
... torsional variables is three (/, h, w) while it is four (/, h1, h2, w) in the case of c-residues. The accommodation of b and c residues into hydrogen bonded folded peptide structures was determined in early studies of oligo b-peptides and hybrid sequences containing b- and c-residues.5–11 A detailed ...
... torsional variables is three (/, h, w) while it is four (/, h1, h2, w) in the case of c-residues. The accommodation of b and c residues into hydrogen bonded folded peptide structures was determined in early studies of oligo b-peptides and hybrid sequences containing b- and c-residues.5–11 A detailed ...
Microstructure and Characteristic of BiVO4 Prepared under
... of sunlight to degrade the organic pollutants. Researchers have used the precipitation, sol–gel and hydrothermal method to prepare BiVO4 [22–24]. Some factors limited the application of precipitation and sol–gel method due to raw material cost, and some extreme reaction condition [23]. The hydrother ...
... of sunlight to degrade the organic pollutants. Researchers have used the precipitation, sol–gel and hydrothermal method to prepare BiVO4 [22–24]. Some factors limited the application of precipitation and sol–gel method due to raw material cost, and some extreme reaction condition [23]. The hydrother ...
Comparison of the electronic structures of four crystalline phases of
... spin ordering within the unit cells and spin-orbit interactions were not included in the calculations. On the basis of the measured Neél temperature for the orthorhombic material,12 we expect the error of that omission to be less than 0.01 eV per unit cell. During the course of this work, we used th ...
... spin ordering within the unit cells and spin-orbit interactions were not included in the calculations. On the basis of the measured Neél temperature for the orthorhombic material,12 we expect the error of that omission to be less than 0.01 eV per unit cell. During the course of this work, we used th ...
Grains and grain boundaries in highly crystalline monolayer
... triangles. This morphological difference allows us to easily identify crystal orientation in optical images. High-resolution STEM images show that despite their sharp appearance in DF-TEM, the edges of both our S-zz and Mo-zz crystals are rough at the nanoscale (Supplementary Fig. S4). In addition t ...
... triangles. This morphological difference allows us to easily identify crystal orientation in optical images. High-resolution STEM images show that despite their sharp appearance in DF-TEM, the edges of both our S-zz and Mo-zz crystals are rough at the nanoscale (Supplementary Fig. S4). In addition t ...
Mineral power point talk
... the surface, it cools. The atoms and molecules in the liquid magmas begin to interact chemically and form minerals. If the magma cools quickly the crystals will be small crystals. If the magma cools slowly the crystals will be large. The second way minerals form is from solutions. A solution can be ...
... the surface, it cools. The atoms and molecules in the liquid magmas begin to interact chemically and form minerals. If the magma cools quickly the crystals will be small crystals. If the magma cools slowly the crystals will be large. The second way minerals form is from solutions. A solution can be ...
PowerPoint lectures on Optical Mineralogy, by J. Winter
... Isotropic media have all ni the same (by definition) What is the shape of an isotropic indicatrix? Amorphous materials or isometric crystals are ...
... Isotropic media have all ni the same (by definition) What is the shape of an isotropic indicatrix? Amorphous materials or isometric crystals are ...
Amorphous phosphates
... An increased elimination of urate is most frequently caused by a high purine diet. Over production, can also be a cause of hyperuricosuria. With a urinary pH greater than 5.5, amorphous urates will be the major crystal form. Below 5.5, uric acid crystals are observed. It is not rare to observe calci ...
... An increased elimination of urate is most frequently caused by a high purine diet. Over production, can also be a cause of hyperuricosuria. With a urinary pH greater than 5.5, amorphous urates will be the major crystal form. Below 5.5, uric acid crystals are observed. It is not rare to observe calci ...
Uranium oxides investigated by X-ray absorption and emission
... found to be different but without significant energy dependence. The experimental spectra of the valence and conduction bands of the uranium oxides are compared to the results of electronic structure calculations available in the literature. α ...
... found to be different but without significant energy dependence. The experimental spectra of the valence and conduction bands of the uranium oxides are compared to the results of electronic structure calculations available in the literature. α ...
CrystEngComm
... reported before.12–14 Their detailed structures were described in the ESI†.15 The new Cu-based coordination polymer composed of furan-2,5-dicarboxylate (Cu(FDC)(H2O)) crystallizes in the monoclinic space group C2/m (no. 12) with one Cu-center on a mirror plane and one Cu-center on a general position ...
... reported before.12–14 Their detailed structures were described in the ESI†.15 The new Cu-based coordination polymer composed of furan-2,5-dicarboxylate (Cu(FDC)(H2O)) crystallizes in the monoclinic space group C2/m (no. 12) with one Cu-center on a mirror plane and one Cu-center on a general position ...
PHYS 4740 Lecture notes 1
... semiconductors have a crystalline structure, which means that they are made of atoms which are arranged in a three-dimensional periodic manner within the constituent crystals. Most engineering materials are polycrystalline in nature in that they are made of many small single crystals which are misor ...
... semiconductors have a crystalline structure, which means that they are made of atoms which are arranged in a three-dimensional periodic manner within the constituent crystals. Most engineering materials are polycrystalline in nature in that they are made of many small single crystals which are misor ...
Rocks and Minerals
... Cleavage and Fracture • The terms cleavage and fracture are used to describe the way a mineral breaks. Cleavage is the tendency of a mineral to split along smooth, definite surfaces. Some minerals, like halite, break into small cubes. Micas cleave along one surface, making layers of thin sheets. Mo ...
... Cleavage and Fracture • The terms cleavage and fracture are used to describe the way a mineral breaks. Cleavage is the tendency of a mineral to split along smooth, definite surfaces. Some minerals, like halite, break into small cubes. Micas cleave along one surface, making layers of thin sheets. Mo ...
Transition metal oxofluorides comprising lone pair elements Shichao Hu
... Recently, with more and more comprehensive theoretical studies based on quantum mechanics, the driving force for lone pair formation has been focused on the interaction of the cation s- and p- orbitals with the oxide anion p-states, instead of pure hybridization of s- and p- orbitals on the cation. ...
... Recently, with more and more comprehensive theoretical studies based on quantum mechanics, the driving force for lone pair formation has been focused on the interaction of the cation s- and p- orbitals with the oxide anion p-states, instead of pure hybridization of s- and p- orbitals on the cation. ...
Optical Properties of Rutile Single Crystals Grown Under Pressure
... commercially available rutile single crystals grown by the Verneuil method, are generally not good enough to use in optical devices because of their dislocation density due to presence of Magnel phases (TiO2-δ) i.e. oxygen deficient phases. The optical quality of the FZ-grown crystals was superior t ...
... commercially available rutile single crystals grown by the Verneuil method, are generally not good enough to use in optical devices because of their dislocation density due to presence of Magnel phases (TiO2-δ) i.e. oxygen deficient phases. The optical quality of the FZ-grown crystals was superior t ...
Solid State Polyselenides and Polytellurides: A Large Variety of Se
... Ba2Ag4Se5 contains two isolated Se2– anions and one Se34– per formula unit, according to the ionic formulation (Ba2+)2(Ag+)4Se34–(Se2–)2. Electronic structure calculations and electrical conductivity measurements confirmed the semiconducting, hence electron precise character of this compound [41]. R ...
... Ba2Ag4Se5 contains two isolated Se2– anions and one Se34– per formula unit, according to the ionic formulation (Ba2+)2(Ag+)4Se34–(Se2–)2. Electronic structure calculations and electrical conductivity measurements confirmed the semiconducting, hence electron precise character of this compound [41]. R ...
CaF Lenses 2
... 3. Quantitative values (scaled to 1 at the maximum) demonstrate the directional dependence of intrinsic birefringence as well as the resulting index anisotropy. (Source: NIST) Canon's design incorporates a combination of [110], [100] and [111] crystal orientations to reduce aberrations, Ware said. ...
... 3. Quantitative values (scaled to 1 at the maximum) demonstrate the directional dependence of intrinsic birefringence as well as the resulting index anisotropy. (Source: NIST) Canon's design incorporates a combination of [110], [100] and [111] crystal orientations to reduce aberrations, Ware said. ...
3.091 Summary Lecture Notes, Fall 2009
... in assigned readings and/or homework are not necessarily covered by these notes. This document should be used as supplemental study material, in addition to reviewing your own notes and doing the assigned readings and homework questions. ...
... in assigned readings and/or homework are not necessarily covered by these notes. This document should be used as supplemental study material, in addition to reviewing your own notes and doing the assigned readings and homework questions. ...
Matter and Minerals Chapter 2
... An isotope is an atom that exhibits variation in its mass number Some isotopes have unstable nuclei that emit particles and energy in a process known as radioactive decay ...
... An isotope is an atom that exhibits variation in its mass number Some isotopes have unstable nuclei that emit particles and energy in a process known as radioactive decay ...
Crystal Structure of Hyaluronidase, a Major Allergen of Bee Venom
... in the structure of quinolinic acid phosphoribosyltransferase (QAPRTase) [29]. Here, the gap that occurs between strands 2 and 3 is partially occupied by the substrate. In Hya there are no hydrogen bonds between strands 1 and 2 whereas in QAPRTase the analogous strands interact through a single hydr ...
... in the structure of quinolinic acid phosphoribosyltransferase (QAPRTase) [29]. Here, the gap that occurs between strands 2 and 3 is partially occupied by the substrate. In Hya there are no hydrogen bonds between strands 1 and 2 whereas in QAPRTase the analogous strands interact through a single hydr ...
Structure of Minerals Structure of minerals
... } An orderly array of atoms chemically bonded to form a particular crystalline structure } Arrangement primarily determined by the sizes of ions ...
... } An orderly array of atoms chemically bonded to form a particular crystalline structure } Arrangement primarily determined by the sizes of ions ...
complexes with bidentate N,N?-bis(b-phenylcinnamaldehyde)
... lower frequencies by 6/20 cm 1 relative to the free ligand upon the coordination of the nitrogen atoms. The observation of a strong band at 2065 cm 1 in the IR spectrum of complex 9 indicates that the NCS ligand in this complex is most probably N-bonded [22]. The 1H NMR data of the Phca2en sugges ...
... lower frequencies by 6/20 cm 1 relative to the free ligand upon the coordination of the nitrogen atoms. The observation of a strong band at 2065 cm 1 in the IR spectrum of complex 9 indicates that the NCS ligand in this complex is most probably N-bonded [22]. The 1H NMR data of the Phca2en sugges ...
Syntheses of Soluble, -Stacking Tetracene Derivatives π
... extensively to tune the electronic and structural properties of organic semiconducting materials because of its strong electronegativity and significantly small size.7a,12 Recently, Watson and co-workers have reported that partial fluorination overcame the herringbone crystal packing of tetracyclic ...
... extensively to tune the electronic and structural properties of organic semiconducting materials because of its strong electronegativity and significantly small size.7a,12 Recently, Watson and co-workers have reported that partial fluorination overcame the herringbone crystal packing of tetracyclic ...
Silicate Minerals
... (Habit) crystals are Minerals Crystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage specific gravity (density) 3 planes of cleavage ...
... (Habit) crystals are Minerals Crystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage specific gravity (density) 3 planes of cleavage ...
Metal ions and phosphate binding in the HNH motif
... The complex crystals were first soaked in EDTA to remove the associated divalent metal ions. X-ray absorption spectra were recorded for the crystals before and after EDTA soaking. The absorption at zinc edge was observed before EDTA soaking and disappeared after ETDA soaking (data not shown). The pr ...
... The complex crystals were first soaked in EDTA to remove the associated divalent metal ions. X-ray absorption spectra were recorded for the crystals before and after EDTA soaking. The absorption at zinc edge was observed before EDTA soaking and disappeared after ETDA soaking (data not shown). The pr ...
Metal ions and phosphate binding in the HNH motif: Crystal
... The complex crystals were first soaked in EDTA to remove the associated divalent metal ions. X-ray absorption spectra were recorded for the crystals before and after EDTA soaking. The absorption at zinc edge was observed before EDTA soaking and disappeared after ETDA soaking (data not shown). The pr ...
... The complex crystals were first soaked in EDTA to remove the associated divalent metal ions. X-ray absorption spectra were recorded for the crystals before and after EDTA soaking. The absorption at zinc edge was observed before EDTA soaking and disappeared after ETDA soaking (data not shown). The pr ...
Synthesis of copper micro-rods with layered nano
... 0.5 to 2 μm. Nano-pores of the size approximately 20 to 100 nm are also observed within the nano-sheets. The porous structures - both the micro-gaps and nano-pores - are believed to be induced by the N2- and carbon-containing gases generated during the decomposition. Interestingly, the piled copper ...
... 0.5 to 2 μm. Nano-pores of the size approximately 20 to 100 nm are also observed within the nano-sheets. The porous structures - both the micro-gaps and nano-pores - are believed to be induced by the N2- and carbon-containing gases generated during the decomposition. Interestingly, the piled copper ...
X-ray crystallography
![](https://commons.wikimedia.org/wiki/Special:FilePath/Zeolite-ZSM-5-vdW.png?width=300)
X-ray crystallography is a tool used for identifying the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their disorder and various other information.Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various materials, especially minerals and alloys. The method also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA. X-ray crystallography is still the chief method for characterizing the atomic structure of new materials and in discerning materials that appear similar by other experiments. X-ray crystal structures can also account for unusual electronic or elastic properties of a material, shed light on chemical interactions and processes, or serve as the basis for designing pharmaceuticals against diseases.In a single-crystal X-ray diffraction measurement, a crystal is mounted on a goniometer. The goniometer is used to position the crystal at selected orientations. The crystal is bombarded with a finely focused monochromatic beam of X-rays, producing a diffraction pattern of regularly spaced spots known as reflections. The two-dimensional images taken at different rotations are converted into a three-dimensional model of the density of electrons within the crystal using the mathematical method of Fourier transforms, combined with chemical data known for the sample. Poor resolution (fuzziness) or even errors may result if the crystals are too small, or not uniform enough in their internal makeup.X-ray crystallography is related to several other methods for determining atomic structures. Similar diffraction patterns can be produced by scattering electrons or neutrons, which are likewise interpreted by Fourier transformation. If single crystals of sufficient size cannot be obtained, various other X-ray methods can be applied to obtain less detailed information; such methods include fiber diffraction, powder diffraction and (if the sample is not crystallized) small-angle X-ray scattering (SAXS).If the material under investigation is only available in the form of nanocrystalline powders or suffers from poor crystallinity, the methods of electron crystallography can be applied for determining the atomic structure.For all above mentioned X-ray diffraction methods, the scattering is elastic; the scattered X-rays have the same wavelength as the incoming X-ray. By contrast, inelastic X-ray scattering methods are useful in studying excitations of the sample, rather than the distribution of its atoms.