Search results for " Optics"
showing 10 items of 5880 documents
Mesoporous Silica Nanoparticles in Chemical Detection: From Small Species to Large Bio-Molecules
2021
A recompilation of applications of mesoporous silica nanoparticles in sensing from the last five years is presented. Its high potential, especially as hybrid materials combined with organic or bio-molecules, is shown. Adding to the multiplying effect of loading high amounts of the transducer into the pores, the selectivity attained by the interaction of the analyte with the layer decorating the material is described. Examples of the different methodologies are presented.
A Comprehensive Survey on Signcryption Security Mechanisms in Wireless Body Area Networks
2022
WBANs (Wireless Body Area Networks) are frequently depicted as a paradigm shift in healthcare from traditional to modern E-Healthcare. The vitals of the patient signs by the sensors are highly sensitive, secret, and vulnerable to numerous adversarial attacks. Since WBANs is a real-world application of the healthcare system, it’s vital to ensure that the data acquired by the WBANs sensors is secure and not accessible to unauthorized parties or security hazards. As a result, effective signcryption security solutions are required for the WBANs’ success and widespread use. Over the last two decades, researchers have proposed a slew of signcryption security solutions to achieve this goal. The la…
The Effect of Paddle Stroke Variables Measured by Trainesense SmartPaddle® on the Velocity of the Kayak
2022
(1) Background: This study aimed to compare key variables of paddle stroke measured by a commercial Trainesense SmartPaddle® against the strain-gauge shaft and investigate how these variables are associated with the velocity of the boat among national-level canoe polo players. (2) Methods: This study involved 14 Finnish national-level canoe polo players. The measurement protocol consisted of three different paddling velocities, which were performed in indoor swimming pools. The velocity of the boat was calculated based on the performance time measured with the laser photocell gate. Canoe polo equipment was used in the study and a SmartPaddle sensor was attached to the paddle blade. A strain…
Femtosecond polarization spectroscopy in molecular gas mixtures: Macroscopic interference and concentration measurements
2000
0021-9606; Raman-induced polarization spectroscopy (RIPS) experiments combined with homodyne detection have been conducted with a femtosecond laser at room temperature and low pressure (p < 2 atm) in CO2-N2 mixtures as well as in air (O2-N2 mixtures). Each molecule of the mixture produces its own time-dependent signal, measured as a series of recurring transients. Macroscopic interference is observed when transients of both molecules overlap in the time domain. This interference leads to a large modification of the signal, which is well reproduced by calculations. The total signal recorded in CO2-N2 or O2-N2 mixtures of known concentration is analyzed in order to measure the polarizability …
BacSr1−cTiO3 perovskite solid solutions: Thermodynamics from ab initio electronic structure calculations
2005
We suggest theoretical prediction for Ba"cSr"1"-"cTiO"3 perovskite solid solutions (BST) combining ab initio DFT/B3PW calculations and alloy thermodynamics. This approach is based on calculations of a series of ordered super-structures in Ba-Sr simple cubic sublattice immersed in the rest TiO"3 matrix. Although these structures are unstable with respect to the decomposition, the results of total energy calculations allow us to extract the necessary energy parameters and to calculate the phase diagram for the solid solutions (alloys). A novel approach applied to the BST system enables to predict that at T>400 K Ba and Sr atom distribution is random. But below this temperature at small c Ba a…
Energy landscapes of ligand-receptor couples probed by dynamic force spectroscopy.
2013
Playing a dominant role in many biochemical processes are the dynamic properties of molecular linkages; examples include cell adhesion, enzyme-catalyzed reactions, and molecular recognition by antibodies. Dynamic force spectroscopy, namely separating molecular bonds under external force ramps has rapidly become a powerful tool to study the rugged energy landscape of noncovalent ligand-receptor bonds. The picture shows a surface and tip-bound pair being pulled apart and the derived potential energy diagram.
Theoretical study of electronically excited cis- and trans-glyoxal
1997
Abstract The equation-of-motion coupled cluster method for excitation energies in the singles and doubles approximation (EOMEE-CCSD) is applied to an investigation of the structure and harmonic frequencies of planar conformers of glyoxal in their first excited singlet states. For the trans-isomer, agreement between calculated harmonic frequencies and observed fundamentals is generally satisfactory, although the theoretical values are slightly more than 10% too high for the carbonyl stretching modes. Parallel calculations of the corresponding ground state properties allow for an empirical prediction of the excited state frequencies in which calculated differences in normal-mode frequencies a…
Ab initio modeling of copper adhesion on regular BaTiO3(001) surfaces
2005
Ab initio calculations have been performed for copper adsorption on a regular, defect-free TiO"2- and BaO-terminated (001) surfaces of a cubic BaTiO"3, using a posteriori HF-CC method as implemented into the CRYSTAL-03 computer code. To clarify the nature of the interfacial bonding, we use slab models of the Cu/BaTiO"3(001) interfaces with different one-side substrate coverages, varied from 1/8 monolayer (ML) up to 1/2 ML, over both TiO"2- and BaO-terminated surfaces. TiO"2 termination has been found to be energetically more favorable for the adsorption of copper atoms. In agreement with previous experimental and theoretical data, our calculations indicate essential contribution of atomic p…
Theoretical study of the derivative hydrocarbons of biphenylene. I. Electronic spectrum of the biphenylene
1969
The electronic spectrum of biphenylene has been studied theoretically. The investigation is based on the semi-empirical LCAO SCF MO method with various degrees of approximations. The results have been analysed with regard to the following two factors: (a) The difference in effective electronegativity between the carbon atoms in the four-membered ring and the other carbon atoms in the molecule. (b) The inclusion of doubly excited configurations in the description of the π-electronic molecular states. The theory satisfactorily interprets the excitation energies and the nature of the electronic transitions. The predictions are particularly affected by the inclusion of the doubly excited config…
Multinuclear Magnetic Resonance Study of 2,4,6-Triarylpyridines, 1-Methyl-2,4,6-Triarylpyridinium, and 2,4,6-Triarylpyrylium Cations
1995
Abstract The H, 13C, 15N, and 19F NMR spectra of 2,4,6-triarylpyridines, 1-methyl-2,4,6-triarylpyridinium and 2,4,6-triarylpyrylium perchlorates have been studied. The H NMR signals of protons 3(5) in the heteroaromatic ring are deshielded due to the polarization of C-H bonds caused by delocalization of the positive charge in pyridinium and pyrylium cations. Generally, conformational and structural variations affect the 13C NMR chemical shifts of all carbons in the heteroaromatic ring. Those of carbons 3(5) can best be related to the electron-donating or electron-accepting ability of substituents. However, both electronic character of substituents and charge of heteroatom itself are needed …