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351.
Journal of Thermal Analysis and Calorimetry - In this article, the behavior of MHD hybrid nanofluid passing through a stretching sheet is examined. The current consideration also flashes the... 相似文献
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Muhammad Ashraf Syed Shaheen Shah Dr. Ibrahim Khan Dr. Md. Abdul Aziz Prof. Nisar Ullah Dr. Mujeeb Khan Dr. Syed Farooq Adil Zainab Liaqat Dr. Muhammad Usman Prof. Wolfgang Tremel Dr. Muhammad Nawaz Tahir 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(23):6973-6984
Tungsten oxide/graphene hybrid materials are attractive semiconductors for energy-related applications. Herein, we report an asymmetric supercapacitor (ASC, HRG//m-WO3 ASC), fabricated from monoclinic tungsten oxide (m-WO3) nanoplates as a negative electrode and highly reduced graphene oxide (HRG) as a positive electrode material. The supercapacitor performance of the prepared electrodes was evaluated in an aqueous electrolyte (1 m H2SO4) using three- and two-electrode systems. The HRG//m-WO3 ASC exhibits a maximum specific capacitance of 389 F g−1 at a current density of 0.5 A g−1, with an associated high energy density of 93 Wh kg−1 at a power density of 500 W kg−1 in a wide 1.6 V operating potential window. In addition, the HRG//m-WO3 ASC displays long-term cycling stability, maintaining 92 % of the original specific capacitance after 5000 galvanostatic charge–discharge cycles. The m-WO3 nanoplates were prepared hydrothermally while HRG was synthesized by a modified Hummers method. 相似文献
354.
Journal of Structural Chemistry - The aim of this work is to study theoretically the geometrical structure, conformational preference, and vibrational properties of rotational isomers of 2- and... 相似文献
355.
In this paper, we have constructed a (2+1)-dimensional wormhole using inhomogeneous and anisotropic distribution of phantom
energy. We have determined the exact form of the equation of state of phantom energy that supports the wormhole structure.
Interestingly, this equation of state is linear but variable one and is dependent only on the radial parameter of the model. 相似文献
356.
Tunable diode-laser absorption of CO2 near 2.7 μm incorporating wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) is used to provide a
new sensor for sensitive and accurate measurement of the temperature behind reflected shock waves in a shock-tube. The temperature
is inferred from the ratio of 2f signals for two selected absorption transitions, at 3633.08 and 3645.56 cm−1, belonging to the ν
1+ν
3 combination vibrational band of CO2 near 2.7 μm. The modulation depths of 0.078 and 0.063 cm−1 are optimized for the target conditions of the shock-heated gases (P∼1–2 atm, T∼800–1600 K). The sensor is designed to achieve a high sensitivity to the temperature and a low sensitivity to cold boundary-layer
effects and any changes in gas pressure or composition. The fixed-wavelength WMS-2f sensor is tested for temperature and CO2 concentration measurements in a heated static cell (600–1200 K) and in non-reactive shock-tube experiments (900–1700 K) using
CO2–Ar mixtures. The relatively large CO2 absorption strength near 2.7 μm and the use of a WMS-2f strategy minimizes noise and enables measurements with lower concentration,
higher accuracy, better sensitivity and improved signal-to-noise ratio (SNR) relative to earlier work, using transitions in
the 1.5 and 2.0 μm CO2 combination bands. The standard deviation of the measured temperature histories behind reflected shock waves is less than 0.5%.
The temperature sensor is also demonstrated in reactive shock-tube experiments of n-heptane oxidation. Seeding of relatively
inert CO2 in the initial fuel-oxidizer mixture is utilized to enable measurements of the pre-ignition temperature profiles. To our
knowledge, this work represents the first application of wavelength modulation spectroscopy to this new class of diode lasers
near 2.7 μm. 相似文献
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M. Farooq Wahab Purnendu K. DasguptaAuthor Vitae Akinde F. KadjoAuthor VitaeDaniel W. Armstrong 《Analytica chimica acta》2016
With increasingly efficient columns, eluite peaks are increasingly narrower. To take full advantage of this, choice of the detector response time and the data acquisition rate a.k.a. detector sampling frequency, have become increasingly important. In this work, we revisit the concept of data sampling from the theorem variously attributed to Whittaker, Nyquist, Kotelnikov, and Shannon. Focusing on time scales relevant to the current practice of high performance liquid chromatography (HPLC) and optical absorbance detection (the most commonly used method), even for very narrow simulated peaks Fourier transformation shows that theoretical minimum sampling frequency is still relatively low (<10 Hz). However, this consideration alone may not be adequate for real chromatograms when an appreciable amount of noise is present. Further, depending on the instrument, the manufacturer's choice of a particular data bunching/integration/response time condition may be integrally coupled to the sampling frequency. In any case, the exact nature of signal filtration often occurs in a manner neither transparent to nor controllable by the user. Using fast chromatography on a state-of-the-art column (38,000 plates), we evaluate the responses produced by different present generation instruments, each with their unique black box digital filters. We show that the common wisdom of sampling 20 points per peak can be inadequate for high efficiency columns and that the sampling frequency and response choices do affect the peak shape. If the sampling frequency is too low or response time is too large, the observed peak shapes will not remain as narrow as they really are – this is especially true for high efficiency and high speed separations. It is shown that both sampling frequency and digital filtering affect the retention time, noise amplitude, peak shape and width in a complex fashion. We show how a square-wave driven light emitting diode source can reveal the nature of the embedded filter. We discuss time uncertainties related to the choice of sampling frequency. Finally, we suggest steps to obtain optimum results from a given system. 相似文献