A new series of piperidine derivatives namely 3,5-dimethyl-2,6-diaryl-1-propionyl-piperidin-4-ones were synthesized. The structure of the compound, 3, ...5-dimethyl-2,6-phenyl-1-propionyl-piperidin-4-one was determined unambiguously using NMR, IR and single crystal X-ray diffraction techniques. DFT and its time dependent version based calculations have been carried out to analyze its ground state electronic structure and to interpret the experimental spectroscopic data. The current study also explores into the spectroscopic property of these piperidine-4-one compounds and proposes these molecules as potential sunscreens and UV filters.
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•Synthesis of 3,5-dimethyl-2,6-diaryl-1-propionyl-piperidin-4-ones.•Characterized by UV, IR, 1H NMR, 13C NMR, HSQC, DEPT-135.•X-ray diffraction of study on compound 3,5-dimethyl-2,6-diphenyl-1-propionyl-piperidin-4-one 3a.•DFT calculation to investigate their electronic structure and UV spectral data.•DFT analysis for the validation of 2, 6 diaryl -piperidin-4-ones as potential sunscreens and UV filters.
Purpose: To evaluate a new rotating anode X‐ray tube from the resonant frequency point of view for stable and safe operation, and to validate a finite element model for insight into X‐ray tube rotor ...dynamics and vibration. Methods: The 3‐dimensional FEM model of the X‐ray tube motor has been developed using ANSYS and COMSOL. The resultant resonant frequency from the FEM simulation is substantiated by experiments. During deceleration of the X‐ray tube, an accelerometer and a corresponding amplifier send the time domain vibration response to a spectrum analyzer which generates the power spectrum. In the frequency domain analysis, a peak signifies large vibrations at that frequency. To corroborate the FEM model, the resonant frequency of the motor assembly without the anode attached was also measured. Lastly, a rough estimate of the resonant frequency can also be observed in angular speed curves which are obtained utilizing a quadrature position sensor. Results: The first mode resonance is expected at 20.3 Hz from the FEM simulation. This result matches closely with the peak at 22.2 Hz in the power spectrum and the location of the abrupt decreasing acceleration (slope) in the speed curve at 22 Hz. Without the anode, the FEM simulation result of 35.1 Hz is equal to the first peak at 35.1 Hz, and the angular acceleration is suddenly reduced at 34.4 Hz. Conclusions: For image‐guided interventional procedures using a hybrid system, the X‐ray tube should create flux at various times requiring repeatedacceleration and deceleration of the motor. Hence it is ideal that the resonant frequency is higher than operational speed, although alternatively the motor could accelerate through the resonant frequency quickly. Design improvements to modify the location of resonance of our motor assemblyare underway using the verified FEM model. NIH R01 EB007626, Richard M. Lucas Foundation
This article uses a case study of urban Canada to explore the contentious issue of spectrum scarcity. Drawing upon infrastructure studies, this article argues for more critical approaches to this ...essential element of contemporary communications. The first part of the article explores positions of various actors in the antagonistic debate regarding spectrum scarcity in the lead up to the Canadian 700 MHz spectrum auction, held in 2014. The second part of the article provides unique empirical data for spectrum traffic on licensed frequencies in a busy urban location. The article reaches an unanticipated conclusion that demonstrates shortcomings in current allocation methods.
The article dwells on assessment of measurement errors when using the laser spectrum analyzers. It presents the analysis results to show that it is possible to carry out a spectral analysis of both ...amplitudes and phases of frequency components of signals and to analyze a changing phase of frequency components of radio signals using interferential methods of measurements. It is found that the interferometers with Mach-Zehnder arrangement are most widely used for measurement of signal phase. A possibility to increase resolution when using the combined method as compared to the other considered methods is shown since with its application spatial integration is performed over one coordinate while time integration is done over the other coordinate that is reached by the orthogonal arrangement of modulators relative each other. The article defines a drawback of this method. It is complicatedness and low-speed because of integrator that disables measurement of spectral components of a radio pulse if its width is less than a temporary aperture. There is a proposal to create an advanced option of the spectrum analyzer in which phase is determined through the signal processing. The article presents resolution when using such a spectrum analyzer. It also reviews the possible options for creating devices to measure the phase components of a spectrum depending on the methods applied to measure a phase. The analysis has shown that for phase measurement a time-pulse method is the most perspective. It is found that the known circuits of digital phase-meters using this method cannot be directly used in spectrum analyzers as they are designed for measurement of the phase only of one signal frequency. In this regard a number of circuits were developed to measure the amplitude and phase of frequency components of the radio signal. It is shown that the perspective option of creating a spectrum analyzer is device in which the phase is determined through the signal processing. The article presents a function diagram of such spectrum analyzer and a time diagram of its operation.
A review of spectral complexes produced by the company VMK-Optoelektronika for atomic emission spectral analysis is presented: Grand-Globula, Grand-Kristall, and Ekspress for the direct atomic ...emission spectral analysis of solid metal and powder samples; Grand-Potok for the express analysis of powders by a spill–injection technique; Grand-Ekspert and Favorit for the express analysis of metals and alloys; a facility for spark sampling Aspekt for the analysis of metal samples with the help of ICP-AES and ICP-MS; Ekspress-Oil for the direct analysis of oils; and Pavlin for the express determination of sodium, lithium, potassium, calcium, barium, cesium, and rubidium in solutions. The composition and technical characteristics of the spectrometers are reported.
Eventually monotone systems are dynamical systems whose solutions preserve a partial order in the initial condition after some initial transient. While monotone systems have a characterization in ...terms of their vector fields, eventually monotone systems have not been characterized in such an explicit manner. In order to provide a characterization, we drew inspiration from the results for linear systems, where eventually monotone (positive) systems are studied using the spectral properties of the system. We extend this spectral characterization to nonlinear systems by employing the Koopman operator framework. We also present a method to certify strong eventual monotonicity with respect to an unknown cone, a tool which to our best knowledge does not exist for monotone systems. These results are illustrated on biologically inspired numerical examples, which highlight the potential applicability of eventual monotonicity.
This paper presents the design of a low-cost real-time (RT) virtual spectrum analyzer. The premises for the creation of the RT instrumentation are introduced. The details of the virtual analyzer ...design are presented. Tests of the instrument, as well as the comparison between the time analysis of the classical and virtual spectrum analyzers, are conducted. Conclusions about the future prospects of such a design approach are iterated.
The structure and characteristics of a modern tool for recording and processing emission spectra, that is, multichannel analyzer of atomic emission spectra (
MAES
), based on multicrystal assemblies ...of photodiode arrays, as well as spectral parameters of the instruments equipped with these analyzers are presented. The analytical potentials of MAES spectrometers are considered.
Repeatability problems, usually accompanied by low accuracy, are often experienced in power measurements, especially in those concerning spread spectrum signals, peculiar to digital wireless ...communication systems, and involving a specified frequency range. For this concern, a new method for power measurements is presented. The method applies original and straightforward digital signal-processing algorithms to the input signal power spectrum, preliminarily provided by optimized versions of well-known estimators, such as those based on weighted overlapped segment averaging and multitaper approaches. The outcomes of many experiments, conducted on spread spectrum signals of third-generation telecommunication systems, confirm the efficacy of the proposed method in assuring reliable and accurate results in various types of power measurement.
Purpose: The purpose of this study was to design an instrument for measuring proton energy spectra, and present energy deposition results that compare calibration runs with two state of the art Monte ...Carlo codes, HETC‐HEDS, and GEANT. Method and Materials: The proton energy spectrum analyzer developed in this study is based on a telescope called the Cosmic Ray telescope of the Effects of radiation (CRaTER), originally designed to achieve characterization of the global lunar radiation environment and its biological impacts. It employs a stack of silicon detectors and tissue‐equivalent plastic (TEP) to establish the linear energy transfer (LET) spectra of cosmic radiation relevant for human and electronic parts considerations. Measured and calculated spectra were obtained using dE/dX= (E0−Ef)/L, where E0 and Ef are the energies of the particles as measured by the silicon detectors at either end of each TEP section and L is the length of the material. Results: Results show a very good agreement between experimental and computer models. A comparison of the peak position shows that HETC‐HEDS simulation of the instrument in a clinical proton beam yield a peak at channel 50. In comparison, the peak channel was 55 with Geant and 57 from the MGH data. The reason for the discrepancy is that the HETC‐HEDS analysis was performed for energies down to 0.2 MeV, while the analyses with GEANT and the MGH data included around 20 more energy channels. Conclusion: An LET energy spectrum was designed and computational testing for proton therapy. Comparisons between calibration runs and two simulation runs using GEANT and HETC‐HEDS show promising results in being able to use the instrument for proton therapy calibration purposes. Future investigations will include analyses for different geometrical configurations, as well as investigating the detector's response to other charged particles.
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