Chemical modification of the bacterial wall to determine sites of metal deposition

1978 ◽  
Vol 36 (2) ◽  
pp. 350-351
Author(s):  
T. J. Beveridge
Keyword(s):  
Electron Scattering ◽  
Metal Salt ◽  
Metal Deposition ◽  
Suitable Model ◽  
X Ray Diffraction ◽  
Subtilis Cell ◽  
Thin Sections ◽  
X Ray ◽  
Section Data ◽  
Metal Impregnation

The Bacillus subtilis cell wall provides a protective sacculus about the vital constituents of the bacterium and consists of a collection of anionic hetero- and homopolymers which are mainly polysaccharidic. We recently demonstrated that unfixed walls were able to trap and retain substantial amounts of metal when suspended in aqueous metal salt solutions. These walls were briefly mixed with low concentration metal solutions (5mM for 10 min at 22°C), were well washed with deionized distilled water, and the quantity of metal uptake (atomic absorption and X-ray fluorescence), the type of staining response (electron scattering profile of thin-sections), and the crystallinity of the deposition product (X-ray diffraction of embedded specimens) determined.Since most biological material possesses little electron scattering ability electron microscopists have been forced to depend on heavy metal impregnation of the specimen before obtaining thin-section data. Our experience with these walls suggested that they may provide a suitable model system with which to study the sites of reaction for this metal deposition.

The petrology of the Mount Padbury mesosiderite and its achondrite enclaves

1966 ◽  
Vol 36 (276) ◽  
pp. 1029-1060 ◽  
Author(s):  
G. J. H. McCall
Keyword(s):  
Microscopic Analysis ◽  
Host Material ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Wide Range ◽  
Varied Range ◽  
Optical Determination

SummaryThe petrography of the Mount Padbury meteorite, previously briefly recorded, is described in some detail. Both the metalliferous host material of the mesosiderite and the varied range of silicate-rich, virtually metal-free enclaves (including both familiar achondrite material and unfamiliar achondrite material) are described. Eucrite, brecciated eucrite, and a peculiar ‘shocked’ form of eucrite (resembling some terrestrial flaser-gabbros) are the calcium-rich achondrite types represented; hypersthene achondrite (including typical diogenite material and unfamiliar material) and olivine achondrite (granular aggregates of olivine not entirely similar to the unique chassignite and single crystals up to 4 in. in length) are the calcium-poor achondrite types represented. The eucrite displays more or less uniform mineralogy, but the mineral constituents are present in varying proportions, and there is a wide range of textural variations recognized. The silicate grain fragments enclosed in the metallic reticulation to form the mesosiderite host material are, significantly, entirely of minerals seen within the achondrite enclaves—plagioclase, hypersthene, pigeonite, olivine, and tridymite.These results include microscopic analysis of thin sections and polished sections, X-ray diffraction studies, optical determination of refractive indices using mineral grain mounts, and chemical analyses.The wider implications of this new and unique meteorite find are briefly considered.

scholarly journals Parkinson’s disease is a type of amyloidosis featuring accumulation of amyloid fibrils of α-synuclein

2019 ◽  
Vol 116 (36) ◽  
pp. 17963-17969 ◽  
Author(s):  
Katsuya Araki ◽  
Naoto Yagi ◽  
Koki Aoyama ◽  
Chi-Jing Choong ◽  
Hideki Hayakawa ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Amyloid Fibrils ◽  
Lewy Bodies ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Β Sheet ◽  
The Brain

Many neurodegenerative diseases are characterized by the accumulation of abnormal protein aggregates in the brain. In Parkinson’s disease (PD), α-synuclein (α-syn) forms such aggregates called Lewy bodies (LBs). Recently, it has been reported that aggregates of α-syn with a cross-β structure are capable of propagating within the brain in a prionlike manner. However, the presence of cross-β sheet-rich aggregates in LBs has not been experimentally demonstrated so far. Here, we examined LBs in thin sections of autopsy brains of patients with PD using microbeam X-ray diffraction (XRD) and found that some of them gave a diffraction pattern typical of a cross-β structure. This result confirms that LBs in the brain of PD patients contain amyloid fibrils with a cross-β structure and supports the validity of in vitro propagation experiments using artificially formed amyloid fibrils of α-syn. Notably, our finding supports the concept that PD is a type of amyloidosis, a disease featuring the accumulation of amyloid fibrils of α-syn.

Spectroscopic and Electrical Studies of Ferrous Sulphate Doped Polyaniline

2012 ◽  
Vol 585 ◽  
pp. 224-227
Author(s):  
Anand Kumar ◽  
Ali Vazid ◽  
Sushil Kumar
Keyword(s):  
Polymer Composites ◽  
Structural Changes ◽  
Metal Salt ◽  
Potassium Dichromate ◽  
Ferrous Sulphate ◽  
Oxidative Polymerization ◽  
Dc Conductivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Visible

Polyaniline (PANI) has been synthesized by chemical oxidative polymerization technique with potassium dichromate oxidant in aqueous hydrochloric acid medium. After polymerization, the polymer so prepared is doped with ferrous sulphate, a transition metal salt, with tetrahydrofuran and water as solvents. The undoped/doped samples were characterized by various techniques such as UV-visible spectroscopy, FTIR spectroscopy, X-ray diffraction and dc conductivity measurements. UV-visible absorption studies revealed the presence of cation/polaron transitions and the presence of direct optical transitions. FTIR studies provide information regarding structural changes in the backbone of PANI with doping concentration. X-ray diffraction patterns of powdered polymer composites showed amorphous nature as mostly conducting polymers exhibit. The dc conductivity of PANI-ferrous sulphate composites were measured by two probe method in pellet form at room temperature (300 K) and found to increase with temperature showing the semiconductor behavior of synthesized polymer composites

Surface Structures from Direct Methods Using a Genetic Algorithm

1997 ◽  
Vol 3 (S2) ◽  
pp. 1047-1048
Author(s):  
E. Landree ◽  
C. Collazo-Davila ◽  
L. D. Marks
Keyword(s):  
Genetic Algorithm ◽  
Electron Scattering ◽  
Three Dimensional ◽  
Direct Methods ◽  
Surface Structures ◽  
Sampling Errors ◽  
X Ray Diffraction ◽  
X Ray ◽  
Search Routine ◽  
Surface Crystal

Two two-dimensional atomic models were constructed to test the application of Direct Methods for solving surface crystal structures (atomic positions are listed in Table 1). The use of Direct Methods to solve three dimensional structures from X-ray diffraction has been well established for several years. However to the best of our knowledge never before had this technique been applied to 2-D surface structures. A Genetic Algorithm (GA) search routine was implemented for exploring possible solutions.The models were constructed using electron scattering factors to calculate the intensities and phases for beams out to 1 Å resolution (Fig. 1). Since electron diffraction from surfaces has been shown to be nearly kinematical X-ray and electron scattering can be handled identically. An error term was applied to the generated intensities to simulate realistic sampling errors. The generated phases for each model were removed and later used to monitor the solutions calculated by the direct methods.

Three-Dimensional Coherent X-Ray Diffraction Microscopy

MRS Bulletin ◽  
2004 ◽  
Vol 29 (3) ◽  
pp. 177-181 ◽  
Author(s):  
Ian K. Robinson ◽  
Jianwei Miao
Keyword(s):  
Electron Microscopy ◽  
Three Dimensional ◽  
Real Space ◽  
Objective Lens ◽  
X Rays ◽  
X Ray Diffraction ◽  
Space Images ◽  
Thin Sections ◽  
X Ray ◽  
Penetration Ability

AbstractX-rays have been widely used in the structural analysis of materials because of their significant penetration ability, at least on the length scale of the granularity of most materials. This allows, in principle, for fully three-dimensional characterization of the bulk properties of a material. One of the main advantages of x-ray diffraction over electron microscopy is that destructive sample preparation to create thin sections is often avoidable. A major disadvantage of x-ray diffraction with respect to electron microscopy is its inability to produce real-space images of the materials under investigation—there are simply no suitable lenses available. There has been significant progress in x-ray microscopy associated with the development of lenses, usually based on zone plates, Kirkpatrick–Baez mirrors, or compound refractive lenses. These technologies are far behind the development of electron optics, particularly for the large magnification ratios needed to attain high resolution. In this article, the authors report progress toward the development of an alternative general approach to imaging, the direct inversion of diffraction patterns by computation methods. By avoiding the use of an objective lens altogether, the technique is free from aberrations that limit the resolution, and it can be highly efficient with respect to radiation damage of the samples. It can take full advantage of the three-dimensional capability that comes from the x-ray penetration. The inversion step employs computational methods based on oversampling to obtain a general solution of the diffraction phase problem.

A new aspect of the “pseudo water” concept of bis(trimethylsilyl)carbodiimide – “pseudohydrates” of aluminum

2018 ◽  
Vol 73 (11) ◽  
pp. 911-918
Author(s):  
Katrin Krupinski ◽  
Erica Brendler ◽  
Robert Gericke ◽  
Jörg Wagler ◽  
Edwin Kroke
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
Quantum Chemical ◽  
Metal Salt ◽  
Similar Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Positional Disorder ◽  
Cp Mas Nmr

AbstractBis(trimethylsilyl)carbodiimide (BTSC), so-called “pseudo water” because of some analogies such as similar (group)electronegativities of Me3Si– vs. H– and –N=C=N– vs. –O–, may form two different kinds of “pseudo hydrates” of metals (M), i.e. M–N(SiMe3)=C=N(SiMe3) and M–N≡C–N(SiMe3)2, derived from its carbodiimide and cyanamide isomeric forms, respectively. With anhydrous AlCl3 in Me3SiCl solution BTSC was shown to be capable of forming both kinds of solvates, i.e. Cl3Al–N(SiMe3)–C≡N(SiMe3) (1) and ((Cl3Al)(Me3Si)NCN)3–Al–(N≡C–N(SiMe3)2)3 (2). Both compounds were isolated as crystalline solids, which undergo condensation reactions upon storage. By single-crystal X-ray diffraction analysis the constitution of 1 was confirmed unambiguously, and quantum chemical calculations (B3LYP/6-311++g(d,p)) confirmed that compound 1 is 6 kcal mol−1 more stable than its hypothetical N,N-bis(trimethylsilyl)cyanamide isomer Cl3Al–N≡C–N(SiMe3)2. Compound 1 represents the first crystallographically confirmed disilylcarbodiimide complex of a metal salt. The molecules of compound 2 are heavily disordered in the solid state (positional disorder of N≡C–N(SiMe3)2 vs. N≡C–N(SiMe3)(AlCl3) and positional disorder of SiMe3 vs. AlCl3 groups in the latter). Therefore, the identity of 2 was additionally confirmed by 13C, 15N, 27Al and 29Si CP/MAS NMR spectroscopy.

scholarly journals Effects of on the Lyotropic Liquid Crystalline Behavior in Nonaqueous and Aqueous Medium

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Ravi K. Shukla ◽  
K. K. Raina
Keyword(s):  
Aqueous Medium ◽  
Liquid Crystalline ◽  
Metal Salt ◽  
Ternary Mixtures ◽  
Aqueous Mixtures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aggregation Behaviour ◽  
Quenching Process ◽  
Fast Quenching

Effects of varying doping concentrations () of on the aggregation behaviour of cationic surfactant in nonaqueous and aqueous medium have been investigated. Mixed and pure lyotropic liquid crystalline LLC phases appeared in nonaqueous and aqueous ternary mixtures due to the fast quenching process and then characterized through polarizing optical microscopy and X-ray diffraction technique. The material parameters corresponding to these ternary nonaqueous and aqueous mixtures were evaluated to understand the mechanisms of deriving forces responsible for the modification of mesophases in the presence of metal salt.

scholarly journals Synthesis, characterization and crystal structure of [Cu2(LH)2]•(ClO4)2. Influence of the weak Cu•••O(perchlorate) interaction on the structure of Cu2N2O2 metallocycle

2014 ◽  
Vol 79 (5) ◽  
pp. 545-556
Author(s):  
Marija Mirkovic ◽  
Nadezda Nikolic ◽  
Dusan Mijin ◽  
Milka Avramov-Ivic ◽  
Agnes Kapor ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cyclic Voltammetry ◽  
Schiff Base ◽  
Ir Spectroscopy ◽  
Metal Complex ◽  
Aprotic Solvent ◽  
Metal Salt ◽  
Protic Solvent ◽  
X Ray Diffraction ◽  
X Ray

The diimine-dioxime ligand, 4,9-diaza-3,10-diethyl-3,9-dodecadiene-2,11-dione bisoxime (LH2), containing a N4 donor set was prepared by Schiff base condensation of 2-hydroxyimino-3-pentanone and 1,4-diaminobutane in two ways: in protic and in aprotic solvent. Higher yield of (LH2) imine was obtained when the synthesis was carried out using protic solvent (C2H5OH) instead of aprotic benzene (78% and 30%, respectively). Cu(II) metal complex of diimine-dioxime was synthesized in CH3OH from metal salt and LH2 in mole ratio 1:1. The isolated complex was characterized by the elemental analysis, IR spectroscopy and cyclic voltammetry. The structure of [Cu2(LH)2]?(ClO4)2 was determined by the single-crystal X-ray diffraction analysis. Comparison with the structurally related diimine-dioxime Cu(II) complexes revealed the influence of the weak Cu???O(perchlorate) interaction on the geometry of the metallocycle.

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