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2021 ◽  
Vol 18 ◽  
Author(s):  
Sajidah Parveen ◽  
Hafiza Ammara Naseem ◽  
Habib Ur Rehman Shah ◽  
Khalil Ahmad ◽  
Tariq Aziz ◽  
...  

Background: A new series of malonic acid-based hydrazide derivatives (BPMPDH, 2HPMPDH, 3HPMPDH, 4HPMPDH, DMPDH) are successfully synthesized by the reaction of malonic ester hydrazide with various substituted aldehydes like salicylaldehyde, benzaldehyde, 4-hydroxy benzaldehyde, 3-hydroxy benzaldehyde and formaldehyde) Methods: metal complexes of prepared hydrazide derivatives were prepared using metals like Cu+2, Zn+2 and Ni+2 via a mild, efficient and convenient method. Newly synthesized compounds were characterized by IR, NMR (1H & 13C), UV/VIS and mass spectrometry. The presence of –C=N- peak at 1600-1700 cm-1 with the absence of NH2 peak at 3500 cm-1 in FTIR spectra. In 1HNMR peak at, 11.00-13.00 ppm for –OH protons and 7.00-9.50 ppm for –NH verified the synthesis of new hydrazide derivatives. The presence of a C-OH sharp peak at 180-190 ppm, a C=O peak at 160-170 ppm and a C=N peak at 140-150 ppm confirmed synthesis. In mass spectra, the molecular ion peaks at 308 m/z, 340 m/z and 156 m/z confirmed synthesis. Synthesized compounds have also been analyzed for their antioxidant, antibacterial, antifungal, chymotrypsin and tyrosinase inhibition activities Result and Conclusion: The results revealed that the 2HPMPDH, 3HPMPDH, 4HPMPDH and their Cu+2 and Zn+2 metal complexes showed more successful inhibition against standard drugs, based on structure activity relationship.


Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 886
Author(s):  
Xiaoyue Tan ◽  
Wujie Wang ◽  
Xiang Chen ◽  
Yiran Mao ◽  
Andrey Litnovsky ◽  
...  

The tungsten (W) foil laminate is an advanced material concept developed as a solution for the low temperature brittleness of W. However, the deformed W foils inevitably undergo microstructure deterioration (crystallization) during the joining process at a high temperature. In this work, joining of the W foil laminate was carried out in a field-assisted sintering technology (FAST) apparatus. The joining temperature was optimized by varying the temperature from 600 to 1400 °C. The critical current for mitigating the microstructure deterioration of the deformed W foil was evaluated by changing the sample size. It is found that the optimal joining temperature is 1200 °C and the critical current density is below 418 A/cm2. According to an optimized FAST joining process, the W foil laminate with a low microstructure deterioration and good interfacial bonding can be obtained. After analyzing these current profiles, it was evident that the high current density (sharp peak current) is the reason for the significant microstructure deterioration. An effective approach of using an artificial operation mode was proposed to avoid the sharp peak current. This study provides the fundamental knowledge of FAST principal parameters for producing advanced materials.


2021 ◽  
Vol 69 (3) ◽  
pp. 199-208
Author(s):  
Karisma Mohapatra ◽  
Dibya Prakash Jena

We propose periodic shells with helical slit to overcome the lacuna in periodic C scatterers, where the first Bragg band is considerably reduced on increasing width of the slit. The key discovery of this research indicates that, by changing the upright slit of the C scatterers to helical slits, larger insertion loss (IL) is achieved around the first Bragg band without compromising the local resonance band. Comparing the performance of periodic shells without slit or cylindrical scatterers, it is found that IL becomes larger at first Bragg band. The pitch, thickness of the shell and width of helical slit can be altered to adjust the resonance of the proposed shells. On decreasing the pitch or increasing the slit width, the resonance band shifts toward high frequencies without much alteration in acoustic attenuation of bandwidth. Additionally, below threshold pitch, the said peak merges with first Bragg band and broadens with prominent IL. The calculated band structure authenticates the bandwidth of the first Bragg band, and the additional sharp peak in IL can be attributed to local resonance of the periodic scatterers.


2021 ◽  
Author(s):  
Jiarun Zhao ◽  
Hanbo Zhang ◽  
Jian Gao ◽  
Wanxin Zhao ◽  
Xiaoguang Zhang

Author(s):  
Jonathan Barnes ◽  
Hansjörg Mixdorff ◽  
Oliver Niebuhr

This chapter reviews commonly recurring tendencies in the phonetic realization of tones, both in intonation and in lexical tone systems. It discusses local interactions between tonal targets, such as tonal coarticulation, dissimilatory H-raising, and rightward target displacement. Non-coarticulatory patterns include globally oriented patterns such as declination, look-ahead upstep, and final lowering as well as interactions between tone and the segmental skeleton, such as segmental anchoring, timing adjustments based on syllable structure or segmental features, and patterns of duration-driven truncation and compression of tone melodies. The chapter also considers morphosyntactically, pragmatically, and metalinguistically conditioned hyperarticulation effects arising from prominence or the Lombard effect. Lastly, it discusses issues relating to contour shape, such as the convexity or concavity of f0 movements, plateau versus sharp peak shapes for f0 maxima, and the propensity for L tones to be accompanied by a falling or dipping f0.


Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Igor Tolstikhin ◽  
Sergei Tarakanov ◽  
Vitalii Kolobov ◽  
Maria Gannibal

Recently experiments on He extraction from an amphibole by the incremental heating unexpectedly revealed that the He release pattern depends on the heating rate. During slow heating (~4 K·min−1) of the amphibole grains, one smooth peak of the He flux from the mineral was observed; in contrast, during fast heating (~40 K·min−1) an additional sharp peak appeared at a temperature about 750 °C. In order to explain these observations, we developed a model of He diffusion from the amphibole, which allowed the calculated He fluxes from the mineral to be reconciled with those observed. From the modelling we derived: (i) the helium diffusion domain size distribution, and evolution of the distribution in the course of incremental heating; (ii) occurrence of the tensile stresses, operating under enhanced temperatures above 700 °C. The stresses are different in sites with the different local thermal expansion of the crystalline lattice and they increase the He diffusion flux. The model can be applied to other minerals (materials).


2020 ◽  
Vol 101 (23) ◽  
Author(s):  
Derrick Van Gennep ◽  
Abdelwahab Hassan ◽  
Huiqian Luo ◽  
Mahmoud Abdel-Hafiez

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Gege Wang ◽  
Zhongxiang Wang ◽  
Liang Chen ◽  
Jianeng Zhou ◽  
Yi Xing

Abstract We search through $\gamma$-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope and find 24 blazars (or candidates) that have a single clear flare event in their 9.5 yr long-term light curves. We define these events as loner flares since each flare stands out significantly above the relatively stable, low-flux light curve. We analyze the LAT data in detail for these 24 sources. The flares in 10 of them are primarily due to a single sharp peak, for which we study by fitting with two different analytic functions. The time durations thus determined for the sharp peaks are in a range of 4–$25\:$d. The $\gamma$-ray spectra of the 24 blazar sources can be described with a power-law or a log-parabola function. We obtain their spectral properties in the flaring and quiescent states, and find that in the flares 16 of the sources have harder emission, three have softer emission, and the other five keep the same emission. We discuss a possible correlation between the differences in photon index in the quiescent and flaring states and photon indices in quiescence. In addition, the sharp peak flares seem to have a tendency of having long time durations and hard emission, possibly related to their physical origin in a blazar jet. Studies of more similar flares will help establish these possible features.


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