Search results for "Cage"

Crystal polymorphism of (μ4–O)-body centered adamantanoid Cu(II) complexes

2016

Abstract Two novel polymorphs of [Cu4(μ4–O)(μ–Cl)6(DASO)4], (DASO = diallyl sulfoxide; C6H10OS), rhombic (C) and triclinic (D), were obtained and examined by single crystal X-ray diffraction analysis at two temperatures, 295(2) and 100(1) K. This study, in addition to our recent work on the tetragonal (A) and trigonal (B) forms of the title compound, allowed determining the nature of polymorphism and temperature-induced phase transitions. It is stated that both the packing arrangement and the displacive transformation integrate these structures, forming the symmetrically and thermodynamically related series: A,B → C → D. The C3h → C4 distortion of Cu(II) trigonal bipyramidal coordination ge…

Light-induced polarization effects in atoms with partially resolved hyperfine structure and applications to absorption, fluorescence, and nonlinear m…

2009

The creation and detection of atomic polarization is examined theoretically, through the study of basic optical-pumping mechanisms and absorption and fluorescence measurements, and the dependence of these processes on the size of ground- and excited-state hyperfine splittings is determined. The consequences of this dependence are studied in more detail for the case of nonlinear magneto-optical rotation in the Faraday geometry (an effect requiring the creation and detection of rank-two polarization in the ground state) with alkali atoms. Analytic formulas for the optical rotation signal under various experimental conditions are presented.

Anisotropy and memory during cage breaking events close to a wall

2016

The slow dynamics in a glassy hard-sphere system is dominated by cage breaking events, i.e., rearrangements where a particle escapes from the cage formed by its neighboring particles. We study such events for an overdamped colloidal system by the means of Brownian dynamics simulations. While it is difficult to relate cage breaking events to structural mean field results in bulk, we show that the microscopic dynamics of particles close to a wall can be related to the anisotropic two-particle density. In particular, we study cage-breaking trajectories, mean forces on a tracked particle, and the impact of the history of trajectories. Based on our simulation results, we further construct two di…

Kerr and Faraday Rotations of Magneto-Optical Multilayers under the Condition of Total Internal Reflection

1999

Hybrid Gold/Silica/Quantum-Dots supramolecular-nanostructures encapsulated in polymeric micelles as potential theranostic tool for targeted cancer th…

2018

Abstract Efficient theranostic tools are today more and more frequently represented by the nano-sized systems. In this paper, polymeric micelles were produced and exploited to encapsulate both an antitumor drug (Doxorubicin) and gold core–shell quantum dots nanoparticles (Au-SiO2/QDs). α,β-poly(N-hydroxyethyl)- dl -aspartamide (PHEA) was functionalized with lipoic acid (LA), polyethylenglycol (PEG), and folic acid (FA) pendant moieties to obtain a synthetic derivative (PHEA-LA-PEG-FA) able to self assemble in aqueous medium giving rise to the formation of polymeric micelles exposing on their surface both targeting groups (FA) and hydrophilic chains (PEG). The drug carrying ability of PHEA-L…

Templated synthesis of a large and flexible covalent porphyrinic cage bearing orthogonal recognition sites.

2012

A large covalent cage incorporating two porphyrins attached by four long and flexible polyether chains each bearing two 3-pyridyl ligands was synthesized from a DABCO-templated olefin metathesis reaction. The X-ray structure of the cage with the DABCO coordinated inside the cavity to the two zinc(II) porphyrins reveals a highly symmetric structure.

P02.40: The influence of maternal age on the association of an isolated fetal intracardiac echogenic focus and fetal aneuploidy

2006

decided to follow up the pregnancy during two weeks and perform the cordocentesis in this time, karyotope was normal. At 26 weeks we found progressive changes in fetal anatomy: heart herniation became larger, left lobe of liver began to protruse, the absence of the sternum and cartilaginous parts of the ribs was confirmed. Patient was offered pregnancy termination because of the impossibility of surgical correction. Radiography, CT and morphology of abortus confirmed ultrasound diagnosis of isolated absence of the sternum and cartilaginous parts of the ribs.

Positive Allosteric Control of Guests Encapsulation by Metal Binding to Covalent Porphyrin Cages

2018

The allosteric control of the receptor properties of two flexible covalent cages is reported. These receptors consist of two zinc(II) porphyrins connected by four linkers of two different sizes, each incorporating two 1,2,3‐triazolyl ligands. Silver(I) ions act as effectors, responsible for an on/off encapsulation mechanism of neutral guest molecules. Binding silver(I) ions to the triazoles opens the cages and triggers the coordination of pyrazine or the encapsulation of N,N′‐dibutyl‐1,4,5,8‐naphthalene diimide. The X‐ray structure of the silver(I)‐complexed receptor with short connectors is reported, revealing the hollow structure with a cavity well‐defined by two eclipsed porphyrins. Rath…

Molecular-dynamics simulation of a glassy polymer melt: Rouse model and cage effect

1999

We report results of molecular-dynamics simulations for a glassy polymer melt consisting of short, linear bead-spring chains. It was shown in previous work that this onset of the glassy slowing down is compatible with the predictions of the mode coupling theory. The physical process of `caging' of a monomer by its spatial neighbors leads to a distinct two step behavior in the particle mean square displacements. In this work we analyze the effects of this caging process on the Rouse description of the melt's dynamics. We show that the Rouse theory is applicable for length and time scales above the typical scales for the caging process. Futhermore, the monomer displacement is compared with si…

Metal-Polyhydride Molecules Are Compact Inside a Fullerene Cage.

2015

Quantum chemical calculations show that metal−hydride molecules are more compact when they are placed inside a fullerene cage than when they are isolated molecules. The metal−hydrogen bond distance in ZrH4 becomes 0.15 A shorter when it is placed inside a C60 cage. Metal−polyhydride molecules with a large number of H atoms such as ScH15 and ZrH16, which are not bound as isolated molecules, are predicted to be bound inside a fullerene cage. It is also shown that two TiH16 clusters are bound inside a bicapped (9,0) carbon nanotube. Possible ways to make metal−hydrides inside C60 and nanotubes are suggested.