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321.
J. H. Zaidi M. Arif I. Fatima S. Ahmed I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(1):123-127
Rapid radiochemical neutron activation analysis (RNAA) procedures were developed and employed for the determination of 32
trace impurities in high purity aluminum thin foils. Anion exchange column chromatography was developed for the sequential
group chemical separation of various elements which helped in reducing the spectral interferences and improving the sensitivity
of the method. The procedure is simple and requires a very short time to separate the elements in three groups for radiometric
assay. To determine very low contents of uranium and thorium,239Np and233Pa as activation products were separated using anion exchange and coprecipitation methods. The impurity contents were found
to be low, therefore, their adverse effects on microelectronic devices would be negligible. Our data could partially be compared
with the data reported in literature. 相似文献
322.
Fredrik Weiland Muhammad Saad Qureshi Jonas Wennebro Christian Lindfors Taina Ohra-aho Hoda Shafaghat Ann-Christine Johansson 《Molecules (Basel, Switzerland)》2021,26(23)
Petrochemical products could be produced from circular feedstock, such as waste plastics. Most plants that utilize syngas in their production are today equipped with entrained flow gasifiers, as this type of gasifier generates the highest syngas quality. However, feeding of circular feedstocks to an entrained flow gasifier can be problematic. Therefore, in this work, a two-step process was studied, in which polypropylene was pre-treated by pyrolysis to produce a liquid intermediate that was easily fed to the gasifier. The products from both pyrolysis and gasification were thoroughly characterized. Moreover, the product yields from the individual steps, as well as from the entire process chain, are reported. It was estimated that the yields of CO and H2 from the two-step process were at least 0.95 and 0.06 kg per kg of polypropylene, respectively, assuming that the pyrolysis liquid and wax can be combined as feedstock to an entrained flow gasifier. On an energy basis, the energy content of CO and H2 in the produced syngas corresponded to approximately 40% of the energy content of the polypropylene raw material. This is, however, expected to be significantly improved on a larger scale where losses are proportionally smaller. 相似文献
323.
Najeeb Alam Khan Muhammad Ali Qureshi Tooba Hameed Saeed Akbar Saif Ullah 《理论物理通讯》2020,72(12):125004-70
In this paper, we propose an innovative chaotic system, combining fractional derivative and sine-hyperbolic nonlinearity with circuit execution. The study of this system is conducted via an analog circuit simulator, using two anti-parallel semiconductor diodes to provide hyperbolic sine nonlinearity, and to function as operational amplifiers. The multi-stability of the system is also enhanced with the help of multi-equilibrium points for distinct real orders of system. The system explores the generation of a four-wing attractor in different phases, both numerically and electronically. By changing the input parameters of the system, different graphs are generated for current flow in state, phase, and space, to confirm the precision of the fractional order derivatives. A reasonable simulation shows that the deliberate circuit provides effective chaos in terms of speed and accuracy, which is comensurate with the numerical simulation. This nonlinear chaotic behavior is utilized to encrypt sound (.wav), images (.jpg), and animated (.gif) data which are a major requirement for the security of communication systems. The proposed circuit performs chaos and cryptographic tasks with high-effective analog computation, and constitutes a novel approach to this area of research. 相似文献
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326.
Dr. Angel T. Garcia-Esparza Dr. Tatsuya Shinagawa Dr. Samy Ould-Chikh Muhammad Qureshi Dr. Xuyuan Peng Dr. Nini Wei Dr. Dalaver H. Anjum Dr. Alain Clo Dr. Tsu-Chien Weng Dr. Dennis Nordlund Dr. Dimosthenis Sokaras Prof. Jun Kubota Prof. Kazunari Domen Prof. Kazuhiro Takanabe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5874-5878
For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2. In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt. Photocatalytic overall water splitting proceeded using MoOx/Pt/SrTiO3 with inhibited water formation from H2 and O2, which is the prevailing back reaction on the bare Pt/SrTiO3 photocatalyst. The Mo coating was stable in acidic media for multiple hours of overall water splitting by membraneless electrolysis and photocatalysis. 相似文献
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329.
Sana Yaqoob Nourina Nasim Rahila Khanam Yan Wang Almas Jabeen Urooj Qureshi Zaheer Ul-Haq Hesham R. El-Seedi Zi-Hua Jiang Farooq-Ahmad Khan 《Molecules (Basel, Switzerland)》2021,26(5)
In search of anti-inflammatory compounds, novel scaffolds containing isonicotinoyl motif were synthesized via an efficient strategy. The compounds were screened for their in vitro anti-inflammatory activity. Remarkably high activities were observed for isonicotinates 5–6 and 8a–8b. The compound 5 exhibits an exceptional IC50 value (1.42 ± 0.1 µg/mL) with 95.9% inhibition at 25 µg/mL, which is eight folds better than the standard drug ibuprofen (11.2 ± 1.9 µg/mL). To gain an insight into the mode of action of anti-inflammatory compounds, molecular docking studies were also performed. Decisively, further development and fine tuning of these isonicotinates based scaffolds for the treatment of various aberrations is still a wide-open field of research. 相似文献
330.
A three-dimensional simulation study is performed for investigating the hydrodynamic behaviors of a cross-flow liquid nitrogen spray injected into an air-fluidized catalytic cracking (FCC) riser of rectangular cross-section. Rectangular nozzles with a fixed aspect ratio but different fan angles are used for the spray feeding. While our numerical simulation reveals a generic three-phase flow structure with strong three-phase interactions under rapid vaporization of sprays, this paper tends to focus on the study of the effect of nozzle fan angle on the spray coverage as well as vapor flux distribution by spray vaporization inside the riser flow. The gas-solid (air-FCC) flow is simulated using the multi-fluid method while the evaporating sprays (liquid nitrogen) are calculated using the Lagrangian trajectory method, with a strong two-way coupling between the Eulerian gas-solid flow and the Lagrangian trajectories of spray. Our simulation shows that the spray coverage is basically dominated by the spray fan angle. The spray fan angle has a very minor effect on spray penetration. The spray vaporization flux per unit area of spray coverage is highly non-linearly distributed along the spray penetration. The convection of gas-solid flow in a riser leads to a significant downward deviation of vapor generated by droplet vaporization, causing a strong recirculating wake region in the immediate downstream area of the spray. 相似文献