An unprecedented porphyrin-pillar[5]arene hybrid ditopic receptor

RSC Advances ◽  
2015 ◽  
Vol 5 (54) ◽  
pp. 43218-43224 ◽  
Author(s):  
Nana Sun ◽  
Xin Xiao ◽  
Chenxi Liu ◽  
Chao Chen ◽  
Jianzhuang Jiang
Keyword(s):  
Supramolecular Complex ◽  
Active Centers ◽  
Host Compound ◽  
Ditopic Receptor ◽  
First Time

A porphyrin-pillar[5]arene hybrid host compound with a ditopic receptor nature was synthesized for the first time, which combines a neutral 1,4-bis(imidazol-1-yl)butane guest by means of its two active centers to form a stable supramolecular complex.

A macrocyclic supramolecular complex obtained from a fullerene ligand bearing two pyridine substituents and a bis-Zn(II)-porphyrin receptor

2006 ◽  
Vol 10 (12) ◽  
pp. 1337-1345 ◽  
Author(s):  
Fettah Ajamaa ◽  
Anne-Marie Albrecht-Gary ◽  
Juan Luis Delgado de la Cruz ◽  
Mourad Elhabiri ◽  
Jean-François Nierengarten ◽  
...  
Keyword(s):  
Binding Sites ◽  
Supramolecular Complex ◽  
Fullerene Derivative ◽  
Ditopic Receptor

A fullerene derivative bearing two pyridine subunits has been designed to allow assembly with a bis- Zn (II)-phorphyrin receptor with two equivalent Zn binding sites separated by about 20 Å. Owing to the complementarity between the bis- Zn (II)-porphyrin receptor and a fullerene ligand bearing two pyridine substituents, the substrate can be clicked on the ditopic receptor, thus leading to a stable non-covalent macrocyclic 1:1 complex.

The scientometrics of literature on smart cities

2019 ◽  
Vol 38 (2) ◽  
pp. 385-398 ◽  
Author(s):  
Shima Moradi
Keyword(s):  
Smart Cities ◽  
Smart Environment ◽  
It Infrastructure ◽  
Active Centers ◽  
Content Type ◽  
Smart Mobility ◽  
First Time ◽  
Conference Papers ◽  
Smart Government ◽  
Highly Cited

Purpose The purpose of this paper is to analyze the research trends in smart cities (SCs) in order to demonstrate the most and the least active fields, researchers, institutions, frontier active centers/authors and funding institutions, as well as drawing the map of the most active countries in this scope. Design/methodology/approach Bibliometric data of 4,696 scientific works were collected from Web of Science, one of the most authentic bibliometric databases, within 1970–2018. The data were analyzed using scientometrics and content analysis methods and visualized by tables, charts and atlases. Findings The results showed an increasing trend in these studies mostly published as conference papers during 48 years. In this period, 0.6 percent of the papers got more than ten citations. Highly cited fields in the area of SCs were orderly smart IT infrastructure, smart government, smart environment, smart mobility, smart energy, smart economy and smart citizen. The geographic atlas of SC studies showed that the frontier countries in SCs were China, Spain and Italy, orderly. China’s main focus was on smart infrastructure while Spain’s focus was smart citizens and smart energy. Italy’s studies were mostly concentrated on smart government, smart mobility and smart environment. In general, it can be concluded that “smart IT infrastructure” was the most noted among the other components of SCs. Originality/value The scientometrics of SC literature has been conducted for the first time.

scholarly journals On the Mechanism of Formation of Conversion Titanium-Containing Coatings

Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 328 ◽  
Author(s):  
Aleksey Abrashov ◽  
Nelya Grigoryan ◽  
Tigran Vagramyan ◽  
Naum Asnis
Keyword(s):  
Steel Substrate ◽  
Titanium Oxides ◽  
Active Centers ◽  
Continuous Film ◽  
Solution Flow ◽  
Linear Rate ◽  
Titanium Coatings ◽  
First Time ◽  
Aluminum Surfaces ◽  
Hydrolysis Of

The present work is devoted to the study of the mechanism of the process of formation of adhesive oxide-titanium coatings on steel, zinc, and aluminum surfaces. For the first time, the following hypothesis has been confirmed experimentally, namely, that nickel, being the first metal to be deposited on a steel substrate, creates active centers on which titanium oxides are formed, because the hydrolysis of hexafluorotitanic acid is adsorbed, which then form a continuous film. The data obtained, regarding the dependence of the coating thickness on the linear rate of the solution flow along the treated surface, indirectly confirm that the formation of insoluble titanium oxides occurs because of the alkalization of the solution adjacent to the surface. It has been established that in the presence of hexavalent molybdenum compounds in the solution as oxidizers, molybdenum is included in the coating in the form of oxides. It has been revealed that in the lower layers of the coating, molybdenum is contained in the form of compounds of molybdenum (V) and (VI), while in the upper layers, it is contained only in the form of the compound of molybdenum (VI).

scholarly journals Fluorescent Calix[4]arene-Oxacyclophane Sensor for Transition Metal Cations

2020 ◽  
Vol 3 (1) ◽  
pp. 40
Author(s):  
Alexandra I. Costa ◽  
Patrícia D. Barata ◽  
José V. Prata
Keyword(s):  
Copper Ions ◽  
Binding Constants ◽  
Supramolecular Complex ◽  
Oxidation States ◽  
Active Centers ◽  
Iodide Ions ◽  
Redox Active ◽  
Counter Ions ◽  
Binding Event ◽  
Sensitivity And Selectivity

The sensing behavior of a calix[4]arene-oxacyclophane-carbazole conjugate (1) towards Cu(I) ions was investigated. Contrary to the noteworthy sensitivity and selectivity previously found for Cu(II), the affinity of 1 for Cu(I) cations is much lower. Through fluorescence titration assays, the apparent binding constants (Ka) for the two ions were determined, showing that an affinity of over thirteen fold was displayed for Cu(II). Two Cu(I) counter-ions were used to determine possible effects on the binding event. It was found that acetate and iodide ions behave similarly, yielding Ka of the same magnitude. Formation of a ground-state supramolecular complex between 1 and Cu(I) ions was not observed on UV-Vis titrations, in contrast to what was previously reported for Cu(II) using the same host. The affinity of 1 for Fe(III), a major biological competitor, was also assessed. The fluorescence of host 1 is quenched by Fe(III) ions although to a lesser extent (32% less efficient than Cu(II)). The study demonstrates that calixarene 1 is able to differentiate copper ions in two common oxidation states using fluorescence techniques, thereby suggesting its application for redox-active centers in biomimetic chemistry.

Step-wise induction, amplification and inversion of molecular chirality through the coordination of chiral diamines with Zn(ii) bisporphyrin

2015 ◽  
Vol 51 (5) ◽  
pp. 895-898 ◽  
Author(s):  
Sk Asif Ikbal ◽  
Sanfaori Brahma ◽  
Sankar Prasad Rath
Keyword(s):  
Supramolecular Complex ◽  
Optically Active ◽  
Chirality Transfer ◽  
Molecular Chirality ◽  
Chiral Diamines ◽  
And Inversion ◽  
First Time ◽  
Origin Of Chirality

A clear structural rationalization of the origin of chirality transfer from an optically active diamine guest to an achiral Zn(ii) bisporphyrin host in a 1 : 1 and 2 : 3 host–guest supramolecular complex has been demonstrated for the first time. During the process, chirality inversion along with amplification was observed.

Annulate lamellae in the Sertoli cells of guinea pig testis after unilateral torsion of the spermatic cord

1984 ◽  
Vol 42 ◽  
pp. 196-197
Author(s):  
J. Chakraborty ◽  
A. P. Sinha Hikim ◽  
J. S. Jhunjhunwala
Keyword(s):  
Sertoli Cells ◽  
Guinea Pigs ◽  
Spermatic Cord ◽  
Present Report ◽  
Cell Types ◽  
Annulate Lamellae ◽  
Spermatogenic Cells ◽  
Electron Microscopic ◽  
Structural Details ◽  
First Time

Although the presence of annulate lamellae was noted in many cell types, including the rat spermatogenic cells, this structure was never reported in the Sertoli cells of any rodent species. The present report is based on a part of our project on the effect of torsion of the spermatic cord to the contralateral testis. This paper describes for the first time, the fine structural details of the annulate lamellae in the Sertoli cells of damaged testis from guinea pigs.One side of the spermatic cord of each of six Hartly strain adult guinea pigs was surgically twisted (540°) under pentobarbital anesthesia (1). Four months after induction of torsion, animals were sacrificed, testes were excised and processed for the light and electron microscopic investigations. In the damaged testis, the majority of seminiferous tubule contained a layer of Sertoli cells with occasional spermatogonia (Fig. 1). Nuclei of these Sertoli cells were highly pleomorphic and contained small chromatinic clumps adjacent to the inner aspect of the nuclear envelope (Fig. 2).

Electron spectroscopic imaging and diffraction

1991 ◽  
Vol 49 ◽  
pp. 706-707
Author(s):  
M. Rühle ◽  
J. Mayer ◽  
J.C.H. Spence ◽  
J. Bihr ◽  
W. Probst ◽  
...  
Keyword(s):  
Materials Science ◽  
Electron Spectroscopic Imaging ◽  
Magnetic Filter ◽  
Magnetic Imaging ◽  
Illumination System ◽  
Probe Size ◽  
Diffraction Patterns ◽  
Fritz Haber ◽  
Koehler Illumination ◽  
First Time

A new Zeiss TEM with an imaging Omega filter is a fully digitized, side-entry, 120 kV TEM/STEM instrument for materials science. The machine possesses an Omega magnetic imaging energy filter (see Fig. 1) placed between the third and fourth projector lens. Lanio designed the filter and a prototype was built at the Fritz-Haber-Institut in Berlin, Germany. The imaging magnetic filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient area detection. The energy dispersion at the exit slit (Fig. 1) results in ∼ 1.5 μm/eV which allows imaging with energy windows of ≤ 10 eV. The smallest probe size of the microscope is 1.6 nm and the Koehler illumination system is used for the first time in a TEM. Serial recording of EELS spectra with a resolution < 1 eV is possible. The digital control allows X,Y,Z coordinates and tilt settings to be stored and later recalled.

A Novel TEM Technique for Characterizing As-Grown CVD Diamond Films

1991 ◽  
Vol 49 ◽  
pp. 956-957 ◽  
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Dark Field ◽  
Growth Surface ◽  
Specimen Preparation ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
First Time ◽  
Microstructural Studies

Microstructural studies by transmission electron microscopy (TEM) of diamond films grown by chemical vapor deposition (CVD) usually involve tedious specimen preparation. This process has been avoided with a technique that is described in this paper. For the first time, thick as-grown diamond films have been examined directly in a conventional TEM without thinning. With this technique, the important microstructures near the growth surface have been characterized. An as-grown diamond film was fractured on a plane containing the growth direction. It took about 5 min to prepare a sample. For TEM examination, the film was tilted about 30-45° (see Fig. 1). Microstructures of the diamond grains on the top edge of the growth face can be characterized directly by transmitted electron bright-field (BF) and dark-field (DF) images and diffraction patterns.

A microscopic marker experiment study on high temperature oxidation of Ni-Al alloy

1986 ◽  
Vol 44 ◽  
pp. 514-515
Author(s):  
Shou-kong Fan
Keyword(s):  
Transport Mechanism ◽  
High Temperature Oxidation ◽  
Transverse Section ◽  
Al Alloy ◽  
Metal Interface ◽  
Electron Microscopic ◽  
Temperature Oxidation ◽  
Analytical Electron ◽  
Microscopic Studies ◽  
First Time

Transmission and analytical electron microscopic studies of scale microstructures and microscopic marker experiments have been carried out in order to determine the transport mechanism in the oxidation of Ni-Al alloy. According to the classical theory, the oxidation of nickel takes place by transport of Ni cations across the scale forming new oxide at the scale/gas interface. Any markers deposited on the Ni surface are expected to remain at the scale/metal interface after oxidation. This investigation using TEM transverse section techniques and deposited microscopic markers shows a different result,which indicates that a considerable amount of oxygen was transported inward. This is the first time that such fine-scale markers have been coupled with high resolution characterization instruments such as TEM/STEM to provide detailed information about evolution of oxide scale microstructure.

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