Macrobicyclic cryptands incorporating amine groups along with oxygen donors that are laterally non-symmetric constitute an important class of organic compounds. These molecules can form inclusion complexes with different transition and main group metal ions. It is also possible to modify the binding characteristics of these compounds through attachment of different groups. Some of these metal complexes can be useful homogeneous catalysts in different organic transformations. If there are chiral centers present in the cryptands, they can be useful in asymmetric syntheses. The three secondary amine groups present in the bridges can be partially or completely derivatized with different fluorophores for fluorescence signaling of transition, inner-transition and heavy metal ions. It is also possible to sequentially attach different fluorophores to study single- as well as multi-step Förster resonance energy transfer. Different donor/acceptor groups can be attached to study second and third order optical nonlinearity. The present article describes several aspects of the chemistry of laterally non-symmetric cryptands and provides future directions for research in this area.
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http://dx.doi.org/10.1039/c7dt00722a | DOI Listing |
IEEE Trans Neural Syst Rehabil Eng
April 2023
Neuropsychologia
March 2022
School of Psychology, University of Surrey, Surrey, UK.
The lateral occipital cortex (LO) has been shown to code the presence of both vertical and horizontal visual symmetry in dot patterns. However, the specific time window at which LO is causally involved in symmetry encoding has not been investigated. This was assessed using a chronometric transcranial magnetic stimulation (TMS) approach.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
August 2021
College of Aerospace Engineering, Chongqing University, Chongqing 400030, People's Republic of China.
A first-order asymptotic analysis of the Griffith energy balance in the Johnson-Kendall-Roberts model of adhesive contact under non-symmetric perturbation of the contact geometry is presented. The pull-off force is evaluated in explicit form. A particular case of adhesive contact between a relatively stiff sphere and an elastic half-space is considered under the assumption that the sphere geometry is changed by the application of an arbitrary lateral normal surface loading.
View Article and Find Full Text PDFJ Bone Miner Res
April 2021
Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, USA.
Vertebral fractures (VFx) are common among older adults. Epidemiological studies report high occurrence of VFx at mid-thoracic and thoracolumbar regions of the spine; however, reasons for this observation remain poorly understood. Prior reports of high ratios of spinal loading to vertebral strength in the thoracolumbar region suggest a possible biomechanical explanation.
View Article and Find Full Text PDFUltrasonics
February 2021
Departments of Radiology and Clinical Neurosciences, University of Calgary, Canada. Electronic address:
Previous work has shown that biaxial driving using two phase-offset orthogonal electric fields (propagation and lateral) improves the efficiency of ferroelectric materials by reducing coercivity and, hence, energy dissipation. In the current investigation, we demonstrated the capability of the biaxial method to steer ultrasound waves in single-element piezoceramic transducers made of prismatic lead zirconate titanate (PZT). We conducted finite element analysis simulations for 133 kHz (model 1) and 470 kHz biaxial (model 2) transducers models.
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