Soft X-ray XAFS Analysis of Cluster Formation Behavior during Natural Aging on an Al–Mg–Si Alloy

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the para substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with p-H, and p-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the p-H and p-allyl derivatives, in contrast with the behaviour of the t-butyl analogue. Lanthanoid complexes of the p-H and p-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the p-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the para substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.

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The Ghosts of Galaxies: Tidal Debris in Clusters

Symposium - International Astronomical Union ◽

10.1017/s0074180900197153 ◽

2004 ◽

Vol 217 ◽

pp. 70-76

Author(s):

Michael D. Gregg ◽

Michael J. West

Keyword(s):

Globular Clusters ◽

Surface Brightness ◽

Large Scale ◽

Dwarf Galaxies ◽

Cluster Formation ◽

X Ray ◽

Cluster Evolution ◽

Low Surface Brightness ◽

Intergalactic Space ◽

Formation And Evolution

Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby Coma and Centaurus clusters both have striking examples of galaxy ghosts, in the form of 100 kpc-long plumes of intergalactic debris. By searching HST archival images, we have found numerous other examples of galaxy ghosts in rich clusters at low redshift, evidence that galaxy destruction and recycling are ubiquitous, important in cluster formation and evolution, and continue to mold clusters at the present epoch. Many ghosts appear in X-ray bright clusters, perhaps signaling a connection with energetic subcluster mergers.The fate of such material has important ramifications for cluster evolution. Our new HST WFPC2 V & I images of a portion of the Centaurus plume reveal that it contains an excess of discrete objects with −12 < MV < −6, consistent with being globular clusters or smaller dwarf galaxies. This tidally liberated material is being recycled directly into the intracluster population of stars, dwarf galaxies, globular clusters, and gas, which may have been built largely from a multitude of similar events over the life of the cluster.

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One-Step Reinforcement and Deacidification of Paper Documents: Application of Lewis Base—Chitosan Nanoparticle Coatings and Analytical Characterization

Coatings ◽

10.3390/coatings10121226 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1226

Author(s):

Zhihui Jia ◽

Chun Yang ◽

Fangnan Zhao ◽

Xiaolian Chao ◽

Yuhu Li ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Chitosan Nanoparticles ◽

Antibacterial Properties ◽

Interaction Mechanism ◽

Accelerated Aging ◽

Natural Aging ◽

Lewis Base ◽

X Ray ◽

Chitosan Nanoparticle ◽

One Step

To delay acidification and deterioration during natural aging, deacidification and reinforcement of paper manuscripts have been the most important technologies to prolong the life of objects. Herein, a novel approach for the conservation of paper manuscripts is proposed using chitosan nanoparticles as Lewis base that leads to both deacidification and strengthening of paper in one-step. Chitosan nanoparticles were prepared through physical ball grinding method and characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle size analyzer (LPSA), Fourier transform infrared spectroscopy (FTIR), and atomic force microscope (AFM). To evaluate the resistance of chitosan nanoparticle coating, the mechanical properties of paper after artificial aging were evaluated using dry heat and hygrothermal accelerated aging methods. The SEM, EDX, and X-ray Photoelectron Spectroscopy (XPS) were used to analyze the interaction mechanism between chitosan and Shuxuan paper. The results show that the coated paper had superior durability with respect to pH, tensile strength, and folding endurance. There was a presence of protonated amines in the form of ammonium salts due to ionic bindings with free H+ in the acidified paper, and the remaining –NH2 could be used as a base reserve. Finally, the resulting coated papers displayed good antibacterial properties.

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Crystallization of Germanium-Carbon Alloys - Structure and Electronic Transport

MRS Proceedings ◽

10.1557/proc-467-427 ◽

1997 ◽

Vol 467 ◽

Cited By ~ 1

Author(s):

T.-M. John ◽

J. Bläsing ◽

P. Veit ◽

T. Drüsedau

Keyword(s):

Electron Microscopy ◽

Crystallite Size ◽

Electronic Transport ◽

Cluster Formation ◽

Electronic Conductivity ◽

Rf Magnetron Sputtering ◽

Cross Sectional ◽

Structural Investigations ◽

X Ray ◽

Transmission Electron

ABSTRACTAmorphous Ge1-xCx alloys were deposited by rf-magnetron sputtering from a germanium target in methane-argon atmosphere. Structural investigations were performed by means of wide and small angle X-ray scattering, X-ray reflectometry and cross-sectional transmission electron microscopy. The electronic transport properties were characterized using Hall-measurements and temperature depended conductivity. The results of X-ray techniques together with the electron microscopy clearly proof the existence of a segregation of the components and cluster formation already during deposition. The temperature dependence of the electronic conductivity in the as-prepared films follows the Mott' T−1/4 law, indicating transport by a hopping process. After annealing at 870 K, samples with x≤0.4 show crystallization of the Ge-clusters with a crystallite size being a function of x. After Ge-crystallization, the conductivity increases by 4 to 5 orders of magnitude. Above room temperature, electronic transport is determined by a thermally activated process. For lower temperatures, the σ(T) curves show a behaviour which is determined by the crystallite size and the free carrier concentration, both depending on the carbon content.

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Early cluster formation during rapid cooling of an Al–Cu–Mg alloy: In situ small-angle X-ray scattering

Scripta Materialia ◽

10.1016/j.scriptamat.2015.06.015 ◽

2015 ◽

Vol 108 ◽

pp. 56-59 ◽

Cited By ~ 15

Author(s):

P. Schloth ◽

A. Menzel ◽

J.L. Fife ◽

J.N. Wagner ◽

H. Van Swygenhoven ◽

...

Keyword(s):

Small Angle ◽

Cluster Formation ◽

Mg Alloy ◽

Rapid Cooling ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

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Ferromagnetic Ge1-xMx (M = Mn, Co, and Fe) Nanowires

MRS Proceedings ◽

10.1557/proc-1032-i14-05 ◽

2007 ◽

Vol 1032 ◽

Author(s):

Yong Jae Cho ◽

chang hyun Kim ◽

jeunghee Park

Keyword(s):

Magnetic Circular Dichroism ◽

Room Temperature Ferromagnetism ◽

Cluster Formation ◽

Magnetization Measurement ◽

X Ray Diffraction ◽

X Ray ◽

Co Doping ◽

X Ray Absorption ◽

Mn Doped ◽

Fe Ions

AbstractWe synthesized Ge and Ge1-xMx (M = Mn, Co, and Fe, x ≤ 0.2) nanowires using thermal vapour transport method. All nanowires consisted of single-crystalline Ge nanocrystals grown uniformly with the [111] direction. High-resolution X-ray diffraction pattern shows no cluster formation for all Ge1-xMx nanowires. The Mn and Fe doping decreases the lattice constant, but not Co doping. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurement revealed that the Mn2+ and Fe2+ ions preferentially occupy the tetrahedral sites, substituting for Ge. We suggest that the Mn or Fe ions produce dopant-acceptor hybridization with host defects in p-type Ge, but not Co ions. The magnetic moment of Mn2+ ions reaches a maximum for x = ∼ 0.1, which is much larger than that of the Fe2+ ions. The magnetization measurement also confirms the room-temperature ferromagnetism of Mn-doped Ge nanowires, which is maximized at x = ∼ 0.1. We conclude that the Mn ions are most efficiently doped into the Ge nanowires to form a ferromagnetic semiconductor.

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Intrinsic and Extrinsic Ferromagnetism in Co-Doped Indium Tin Oxide Revealed Using X-Ray Magnetic Circular Dichroism

Advances in Condensed Matter Physics ◽

10.1155/2017/2836254 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

A. M. H. R. Hakimi ◽

F. Schoofs ◽

M. G. Blamire ◽

S. Langridge ◽

S. S. Dhesi

Keyword(s):

Thin Films ◽

Circular Dichroism ◽

Tin Oxide ◽

Indium Tin Oxide ◽

Magnetic Circular Dichroism ◽

Cluster Formation ◽

X Ray ◽

Ito Thin Films ◽

Circular Dichroïsm ◽

Co Doped

The effects of high-temperature annealing on ferromagnetic Co-doped Indium Tin Oxide (ITO) thin films have been investigated using X-ray diffraction (XRD), magnetometry, and X-Ray Magnetic Circular Dichroism (XMCD). Following annealing, the magnetometry results indicate the formation of Co clusters with a significant increase in the saturation magnetization of the thin films arising from defects introduced during cluster formation. However, sum rule analysis of the element-specific XMCD results shows that the magnetic moment at the Co sites is reduced after annealing. The effects of annealing demonstrate that the ferromagnetism observed in the as-deposited Co-doped ITO films arises from intrinsic defects and cannot be related to the segregation of metallic Co clusters.

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Some physicochemical studies on organic eutectics and 1:1 addition compound; p-phenylenediamine – benzoic acid system

Canadian Journal of Chemistry ◽

10.1139/v89-039 ◽

1989 ◽

Vol 67 (2) ◽

pp. 239-244 ◽

Cited By ~ 12

Author(s):

U. S. Rai ◽

K. D. Mandal

Keyword(s):

Phase Diagram ◽

Benzoic Acid ◽

Cluster Formation ◽

Growth Front ◽

Spectral Studies ◽

Acid System ◽

Addition Compound ◽

X Ray Diffraction ◽

X Ray ◽

Entropy Of Fusion

The phase diagram of p-phenylenediamine – benzoic acid system, determined by the thaw–melt method, shows the formation of two eutectics and a 1:1 addition compound. The linear velocity of crystallization of pure components, eutectics and addition compound, determined by measuring the movement of growth front in a capillary, suggests that crystallization data obey the Hillig–Turnbull equation. Using experimental values of heats of fusion, entropy of fusion and excess thermodynamic functions were calculated and the results are explained on the basis of cluster formation in the melts. X-ray diffraction data infer that these eutectics are not simply the mechanical mixture of the two components and there is preferential ordering of atomic planes during their formation. The infrared spectral studies suggest the formation of intermolecular hydrogen bonding between the components forming the molecular complex. Keywords: organic eutectics, growth kinetics, phase diagram, thermochemistry, X-ray diffraction studies.

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