scholarly journals X-ray Diffraction Study of Directional Solidification Ledeburite

2015 ◽  
Vol 15 (3) ◽  
pp. 71-76 ◽  
Author(s):  
M. Trepczyńska-Łent ◽  
T. Szykowny
Keyword(s):  
Eutectic Growth ◽  
Crystallographic Analysis ◽  
Argon Atmosphere ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
Growth Morphology ◽  
Cast Irons ◽  
Constant Temperature Gradient ◽  
X Ray ◽  
Carbide Particles

Abstract Directionally solidified sample of Fe-Fe3C eutectic alloy were produced under an argon atmosphere in a vacuum Bridgman-type furnace to study the eutectic growth with ν = 167 μm/s pulling rate and constant temperature gradient G = 33.5 K/mm. Since how the growth texture of eutectic cementite is related to its growth morphology remains unclear, the current study aims to examine this relationship. The technique such as X-ray diffraction, have been used for the crystallographic analysis of carbide particles in white cast irons.

A TEM investigation of a hyper-eutectic lead-tin alloy

1988 ◽  
Vol 46 ◽  
pp. 562-563
Author(s):  
John A. Sutliff
Keyword(s):  
Volume Diffusion ◽  
Eutectic Mixture ◽  
Precipitation Reaction ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffusion Controlled ◽  
Discontinuous Precipitation Reaction ◽  
Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

Structural Evaluation of Ti-22.2Si-11.1B Powders Milled with PCA Addition

2008 ◽  
Vol 591-593 ◽  
pp. 147-153
Author(s):  
Gilbert Silva ◽  
Erika Coaglia Trindade Ramos ◽  
N.S. da Silva ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Ball Mill ◽  
Milling Process ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Evaluation ◽  
Equilibrium Structures ◽  
Scanning Electron

A large amount of the Ti6Si2B compound can be formed by mechanical alloying and subsequent heat treatment from the elemental Ti-22.2at%Si-11.1at%B powder mixture, but the yield powder after ball milling is reduced due to an excessive agglomeration of ductile particles on the balls and vial surfaces. This work reports on the structural evaluation of Ti-22.2at%Si-11.1at%B powders milled with PCA addition, varying its amount between 1 and 2 wt-%. The milling process was carried out in a planetary ball mill under argon atmosphere, and the milled powders were then heated at 1200oC for 1h under Ar atmosphere in order to obtain equilibrium structures. Samples were characterized by X-ray diffraction, scanning electron microscopy, and thermal analysis. Results revealed that the PCA addition reduced the excessive agglomeration during the ball milling of Ti-22.2at-%Si-11.1at-%B powders. After heating at 1200oC for 1h, the Ti5Si3, Ti3O and/or Ti2C phases were preferentially formed in Ti-22.2at%Si-11.1at%B powders milled with PCA addition, and the Ti6Si2B formation was inhibited.

scholarly journals Получение карбида бора в низковольтной электрической дуге постоянного тока, инициированной в открытом воздушном пространстве

2018 ◽  
Vol 44 (14) ◽  
pp. 26 ◽  
Author(s):  
А.Я. Пак ◽  
Г.Я. Мамонтов
Keyword(s):  
Boron Carbide ◽  
Arc Discharge ◽  
Electron Microscopic Examination ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Vacuum Equipment ◽  
X Ray ◽  
Gas Atmosphere ◽  
Average Size ◽  
Carbide Particles

AbstractWe describe a method of obtaining ultrafine boron carbide (B_13C_2) powder using the effect of a dc electric arc on a mixture of initial reactants containing carbon and boron. A peculiarity of the proposed method is that it can be implemented using arc discharge operating in open air without any vacuum equipment and protective inert gas atmosphere. X-ray diffraction data showed that the synthesized product in the general case contained three crystalline phases: boron carbide (B_13C_2), graphite (C), and boron oxide (B_2O_3). Electron-microscopic examination showed that the average size of boron carbide particles ranged from ~50 nm to ~2 μm.

scholarly journals Dielectric Function of AlN Grown on Si (111) by MBE

1999 ◽  
Vol 572 ◽  
Author(s):  
Stefan Zollner ◽  
Atul Konkar ◽  
R. B. Gregory ◽  
S. R. Wilson ◽  
S. A. Nikishin ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Buffer Layers ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Growth Morphology ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dimensional Growth ◽  
Peak Widths

ABSTRACTWe measured the ellipsometric response from 0.7–5.4 eV of c-axis oriented AlN on Si (111) grown by molecular beam epitaxy. We determine the film thicknesses and find that for our AlN the refractive index is about 5–10% lower than in bulk AlN single crystals. Most likely, this discrepancy is due to a low film density (compared to bulk AlN), based on measurements using Rutherford backscattering. The films were also characterized using atomic force microscopy and x-ray diffraction to study the growth morphology. We find that AlN can be grown on Si (111) without buffer layers resulting in truely two-dimensional growth, low surface roughness, and relatively narrow x-ray peak widths.

scholarly journals Solid-liquid interface morphology of white carbide eutectic during directional solidification

2017 ◽  
Vol 62 (1) ◽  
pp. 365-368 ◽  
Author(s):  
M. Trepczyńska-Łent
Keyword(s):  
Longitudinal Section ◽  
Argon Atmosphere ◽  
Liquid Interface ◽  
Interface Morphology ◽  
Directionally Solidified ◽  
Constant Temperature Gradient ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Scanning Electron ◽  
Made In

AbstractIn this paper the analysis of solid-liquid interface morphology in white carbide eutectic was made. In a vacuum Bridgman-type furnace, under an argon atmosphere, directionally solidified sample of Fe - C alloy was produced. The pulling rate was v = 125 μm/s (450 mm/h) and constant temperature gradient G = 33.5 K/mm. The microstructure of the sample was frozen. The microstructure of the sample was examined on the longitudinal section using an light microscope and scanning electron microscope.

scholarly journals A putative siderophore-interacting protein from the marine bacteriumShewanella frigidimarinaNCIMB 400: cloning, expression, purification, crystallization and X-ray diffraction analysis

2016 ◽  
Vol 72 (9) ◽  
pp. 667-671 ◽  
Author(s):  
Inês B. Trindade ◽  
Bruno M. Fonseca ◽  
Pedro M. Matias ◽  
Ricardo O. Louro ◽  
Elin Moe
Keyword(s):  
Iron Acquisition ◽  
Crystallographic Analysis ◽  
Monoclinic Space Group ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
Interacting Protein ◽  
X Ray ◽  
Cell Parameters ◽  
Unit Structure ◽  
Shewanella Frigidimarina

Siderophore-binding proteins (SIPs) perform a key role in iron acquisition in multiple organisms. In the genome of the marine bacteriumShewanella frigidimarinaNCIMB 400, the gene tagged as SFRI_RS12295 encodes a protein from this family. Here, the cloning, expression, purification and crystallization of this protein are reported, together with its preliminary X-ray crystallographic analysis to 1.35 Å resolution. The SIP crystals belonged to the monoclinic space groupP21, with unit-cell parametersa= 48.04,b= 78.31,c= 67.71 Å, α = 90, β = 99.94, γ = 90°, and are predicted to contain two molecules per asymmetric unit. Structure determination by molecular replacement and the use of previously determined ∼2 Å resolution SIP structures with ∼30% sequence identity as templates are ongoing.

X-ray diffraction has limited applicability in investigation of milk tampering

2019 ◽  
Vol 86 (3) ◽  
pp. 337-340
Author(s):  
Ana Paula Pavão Battaglini ◽  
Alexandre Urbano ◽  
Vanerli Beloti ◽  
Edson Antonio Rios ◽  
Juliana Ramos Pereira ◽  
...  
Keyword(s):  
Sodium Citrate ◽  
Freezing Point ◽  
Raw Milk ◽  
Physicochemical Analysis ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Water Addition ◽  
X Ray ◽  
Freeze Dried ◽  
Limited Applicability

AbstractThe aim of this work was to use X-ray diffraction to identify substances used for adulteration of raw milk and to determine if crystallographic analysis can detect extraneous substances in milk. Two unknown substances were sent anonymously by employers linked to the dairy chain, who claimed that they were added directly in milk prior to water addition by truck drivers. The samples were analyzed by X-ray diffraction and submitted to physicochemical analysis. The first substance was identified by X-ray diffraction as sodium citrate, complying with its physicochemical attributes, such as the powerful ability to decrease the freezing point. The second substance was identified by X-ray diffraction as sucrose and this result was also in agreement with its ability to increase the density, decrease the freezing point and finally, to be positive for sucrose in the resorcinol qualitative test. To evaluate if X-ray diffraction can detect extraneous substances already mixed in milk, fresh raw milk samples tampered with urea, sodium hydroxide, sodium citrate and sucrose were freeze dried and analyzed by X-ray diffraction, with no detection of any extraneous substances at any percentage. This is the first report of attempted diagnosis of extraneous substances in milk by X-ray diffraction. However, this technique can be useful only when applied to identify substances used for adulteration prior to its dilution in milk, since the amorphous nature of milk seems to be a limitation for the accurate detection of extraneous substances.

scholarly journals Crystallization and preliminary crystallographic analysis of manganese lipoxygenase

2014 ◽  
Vol 70 (4) ◽  
pp. 522-525 ◽  
Author(s):  
Anneli Wennman ◽  
Ernst H. Oliw ◽  
Saeid Karkehabadi
Keyword(s):  
Expression System ◽  
Crystallographic Analysis ◽  
Gaeumannomyces Graminis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Apparent Homogeneity ◽  
Structural Differences ◽  
Position Specificity ◽  
Take All

Lipoxygenases constitute a family of nonhaem metal enzymes with catalytic iron or, occasionally, catalytic manganese. Lipoxygenases oxidize polyunsaturated fatty acids with position specificity and stereospecificity to hydroperoxides, which contribute to inflammation and the development of cancer. Little is known about the structural differences between lipoxygenases with Fe or Mn and the metal-selection mechanism. APichia pastorisexpression system was used for the production of the manganese lipoxygenase of the take-all fungus of wheat,Gaeumannomyces graminis. The active enzyme was treated with α-mannosidase, purified to apparent homogeneity and subjected to crystal screening and X-ray diffraction. The crystals diffracted to 2.6 Å resolution and belonged to space groupC2, with unit-cell parametersa= 226.6,b= 50.6,c= 177.92 Å, β = 91.70°.

scholarly journals Crystallization and preliminary X-ray crystallographic analysis of carboxyl-terminal region 4 of SigR fromStreptomyces coelicolorA3(2)

2014 ◽  
Vol 70 (6) ◽  
pp. 747-749
Author(s):  
Keon Young Kim ◽  
Sunmin Kim ◽  
Jeong Kuk Park ◽  
HyoJin Song ◽  
SangYoun Park
Keyword(s):  
Streptomyces Coelicolor ◽  
Crystallographic Analysis ◽  
Terminal Region ◽  
Full Length ◽  
Spectrometric Analysis ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Carboxyl Terminal

Full-length SigR fromStreptomyces coelicolorA3(2) was overexpressed inEscherichia coli, purified and submitted to crystallization trials using either polyethylene glycol 3350 or 4000 as a precipitant. X-ray diffraction data were collected to 2.60 Å resolution under cryoconditions using synchrotron X-rays. The crystal packs in space groupP43212, with unit-cell parametersa=b= 42.14,c= 102.02 Å. According to the Matthews coefficient, the crystal asymmetric unit cannot contain the full-length protein. Molecular replacement with the known structures of region 2 and region 4 as independent search models indicates that the crystal contains only the −35 element-binding carboxyl-terminal region 4 of full-length SigR. Mass-spectrometric analysis of the harvested crystal confirms this, suggesting a crystal volume per protein weight (VM) of 2.24 Å3 Da−1and 45.1% solvent content.

scholarly journals Cloning, expression, purification, crystallization and preliminary crystallographic analysis of 5-aminolaevulinic acid dehydratase fromBacillus subtilis

2010 ◽  
Vol 66 (9) ◽  
pp. 1053-1055 ◽  
Author(s):  
Qianda Lu ◽  
Jinming Ma ◽  
Hui Rong ◽  
Jun Fan ◽  
Ye Yuan ◽  
...  
Keyword(s):  
Crystallographic Analysis ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
Gene Encoding ◽  
Data Set ◽  
X Ray ◽  
Aminolaevulinic Acid ◽  
Acid Dehydratase ◽  
Strain Bl21 ◽  
Aminolaevulinic Acid Dehydratase

5-Aminolaevulinic acid dehydratase (ALAD), a crucial enzyme in the biosynthesis of tetrapyrrole, catalyses the condensation of two 5-aminolaevulinic acid (ALA) molecules to form porphobilinogen (PBG). The gene encoding ALAD was amplified from genomic DNA ofBacillus subtilisand the protein was overexpressed inEscherichia colistrain BL21 (DE3). The protein was purified and crystallized with an additional MGSSHHHHHHSSGLVPRGSH– tag at the N-terminus of the target protein. Diffraction-quality single crystals were obtained by the hanging-drop vapour-diffusion method. An X-ray diffraction data set was collected at a resolution of 2.7 Å.

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