Structural and electronic properties of c-Fe2Zr, t-FeZr2 and o-FeZr3 intermetallic phases in the presence of s-, p- and d-block fission metals (FMs), viz., Rb, Sr, In, Sn, Sb, Te, Cs, Ba, Y, Nb, Mo, ...Tc, Ru, Rh, Pd, Ag and Cd are studied using density functional theory (DFT). The mono-vacancy and di-vacancy formation energies of Fe and Zr in these intermetallics are also calculated. It has been found that s-block FMs are less weakly bounded to the intermetallics than the p− and d−block FMs. The solution energies of p− and d−block fission atoms are either slightly positive or negative. The high solution energies of s-block FMs suggest that these FMs are highly insoluble in the Fe-Zr intermetallics. The solution energy hierarchy of the FMs follow the trend as Cs > Rb > Ba > Sr > Ag > Cd > Y > Mo > Nb > In > Te > Sn > Tc > Sb > Pd > Ru > Rh. We also report the site preferences of these FMs in Fe-Zr intermetallics based on their incorporation/solution energies. The electronic property analysis indicate a predominant metallic bonding with small covalent and ionic contributions. Finally, these intermetallics have been compared in terms of their potentials to accommodate these FMs.
Herein we investigated the molecular mechanism of action of the citrus flavonoid, quercetin in skeletal muscle cells (L6 myotubes). Taking advantage of protein kinase inhibitors, we proved that the ...effect of quercetin on 2-NBDG uptake in L6 myotubes was not through insulin signaling pathway, but through adenosine monophosphate kinase (AMPK) pathway and its downstream target p38 MAPK. An increase in the cellular AMP to ATP ratio on pretreatment may account for AMPK activation which was coupled with a transient change in mitochondrial membrane potential. In addition, quercetin triggered a rise in intracellular calcium suggesting that calcium-calmodulin mediated protein kinase (CaMKK) may also be involved. Quercetin shared a similar mechanism with the well-known drug metformin, highlighting it as a promising compound for the management of type 2 diabetes. The AMPK signaling pathway could contribute to correction of insulin resistance through bypassing the insulin-regulated system for GLUT4 translocation.
We report the findings of an experimental and theoretical analysis of the structural, electronic, and vibrational characteristics of Ba2GdRuO6 and Sr2GdRuO6 double perovskite ruthenates. The samples ...of Ba2GdRuO6 and Sr2GdRuO6 were synthesized using solid state reaction method. The samples have been characterized by X-ray diffraction (XRD) technique where phase purity and space group information have been obtained using FullProf Rietveld refinement method. The Rietveld-fitted XRD patterns show that Ba2GdRuO6 has a single-phase cubic structure with space group Fm3¯m and that Sr2GdRuO6 has a monoclinic structure with space group P21∕n. The vibrational properties were measured, via., Raman spectroscopy performed at room temperature. The structures predicted from XRD were studied theoretical using accurate plane wave pseudo-potential method based on density functional theory (DFT) with Hubbard parameter, U (DFT+U). The Ba2GdRuO6 is found to be metallic with difference in density of states for spin up and spin down electrons; whereas Sr2GdRuO6 is insulating with a band gap of 4.0 eV. The vibrational analysis of pervoskites shows A1g, Eg and 2F2g, Raman active modes for Ba2GdRuO6; while for Sr2GdRuO6 the observed active modes were Ag and Bg, respectively. It’s worth noting that the experimentally measured values match those predicted by our DFT calculations.
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•An integrated experimental and theoretical approach for Ru based double perovskites has been discussed.•Future perspective to explore the role of rare-earth metal ions to further tune the electronic properties of such perovskites has been discussed.•The interesting interplay between Ru and transition metal ions can be understood as a transition from metallic for Ba2GdRuO6 to insulating behavior for Sr2GdRuO6.
•Thermal performance of a copper made microchannel heat sink is investigated.•Silver nanoparticles are synthesized and used in the cooling loop.•37% enhancement in overall thermal performance of the ...system is reported.•Small penalty for friction factor and pressure drop is reported.•Fouling was found to reduce the thermal performance of the system.
Thermal performance of a copper-made heat sink with rectangular microchannel was assessed within laminar flow regime. Silver nanoparticles were synthesized and dispersed into the deionized water as a potential coolant. Pressure drop, friction factor, heat transfer coefficient and fouling thermal resistance parameter of the system were experimentally investigated for mass concentrations of 0.01%, 0.05%, and 0.1%. Results showed that the heat transfer coefficient of the microchannel is enhanced when deionized water (as a traditional coolant) is replaced with the nanofluid. Importantly, a small increase in pressure drop, friction factor and fouling thermal resistance parameter were reported when nanofluid is used in the system. With an increase in the flow rate and mass concentration of nanofluid, the heat transfer coefficient and pressure drop of the Microchannel Heat Sink (MCHS) increased. Likewise, the local heat transfer coefficient and overall thermal resistance of the microchannel decreased along with the length of the microchannel. The highest heat transfer coefficient (as a thermal performance index) was also seen in the entrance region of the microchannel. The highest value for the fouling thermal resistance parameter was observed for the highest mass concentration of nanofluid which was 1.07 for wt.% = 0.1. The flow rate of fluid was found to enhance the fouling thermal resistance parameter over the 1000 min of the operation. Despite the enhancement in the fouling thermal resistance parameter and friction factor, there was an optimum concentration for silver-water nanofluid in which the overall thermal performance of the system was maximized such that the overall thermal performance of the system can be enhanced up to 37% at Reynolds number 1400 and at wt.% = 0.05.
•Experimental investigation on thermal performance of microchannel heat sink.•Aqueous CNT nanofluids at wt.%=0.05–0.1 were used as the coolant.•Lower temperature profile and higher HTC were recorded ...for nanofluids.•Fouling thermal resistance showed an asymptotic behavior over the time.
Experimental investigation is performed on the thermal performance of a copper-made heat sink with rectangular microchannel. Carbon nano tube aqueous nanofluid is used as a coolant inside the microchannel at mass concentrations of 0.05–0.1%. Influence of different operating parameters including applied heat flux, fluid flow rate and mass concentration of nanofluid on the local and average heat transfer coefficients, fouling thermal resistance, overall thermal resistance and local (axial) temperature profile is investigated. Results showed the higher heat transfer coefficient and lower temperature profile inside the heat sink in comparison with the base fluid (water). Fluid flow rate and mass concentrations were found to increase the heat transfer coefficient significantly, while slight improvement was seen when higher heat fluxes were applied into the microchannel heat sink. Fouling thermal resistance was found to asymptotically increase with an increase in operating time and strongly depends on the concentration of nanofluid such that the required operating time to reach a constant value was different. The higher the mass concentration, the lower operating time is required to reach the constant fouling thermal resistance. However, overall thermal resistance of the microchannel (without considering the fouling effect) was found to linearly decrease with the mass concentration of nanofluid.
Amorphous ternary metal borides in the form of Co-M-B (where, M = Fe, Ni, Cu, Mo, Mn, W or Cr) were developed for electrocatalytic hydrogen evolution in neutral and alkaline solutions. Except for ...Co-Cr-B, all the Co-M-B catalysts showed better hydrogen evolution rate than Co-B, with the lowest overpotential of 95 mV and 67 mV (at 10 mA/cm2) recorded for optimized Co-Mo-B catalyst, in pH 7 and pH 14, respectively. The reasons for enhancement in electrocatalytic rate, with inclusion of a second metal in Co-B, were investigated by considering several material related factors, such as, physical and electrochemical surface area, turn-over frequency, surface elemental states & composition and charge-transfer resistance. These experimental results were complemented with computational investigations to identify the most suitable sites for hydrogen adsorption and determine their H-adsorption energies. In the end, industrial feasibility of the developed Co-M-B catalysts was illustrated by performing stability and recycling tests.
Motivated by the wide-band-gap semiconductor properties of Zn-monochalcogenides (Zn-X; X:S, Se and Te), especially for their crucial industrial applications, we use a first-principles approach to ...investigate the B3 (zinc blende type) to B1 (rock salt type) structural transitions in this series of compounds as a function of pressure and temperature. Under static conditions (i.e.,
T
= 0 K), the transition pressure is found to steadily drop from ZnS to ZnTe via intermediate ZnSe. Our calculations within quasi-harmonic approximation yield negative Clapeyron slopes of the B3–B1 phase boundaries for all the three compounds, where ZnTe has the highest negative slopes. We also present a completely new set of calculations for the thermoelasticity of Zn-X phases in the temperature range 0–1100 K. This article then addresses how the B3–B1 phase transitions can influence the mechanical as well as electronic properties of Zn-X. This phase transition always results in a softening of their elastic constant
C
12
; however,
C
11
and
C
44
get stiffened. The same structural transition switches a semiconductor to conductor-type electronically favorable transition, as inferred from their high-pressure electronic structure. Among the three Zn-X compounds, ZnTe becomes the most metallic phase following the B3–B1 transition. Our findings offer a novel explanation for the complete loss of semiconductor property of these monochalcogenides at elevated pressures.
Purpose The purpose of this study is to analyze the utility of Convolutional Neural Network (CNN) in medical image analysis. In this study, deep learning (DL) models were used to classify the X-ray ...into COVID, viral pneumonia, and normal categories. Materials and Methods In this study, we have compared the results 9 layers CNN model (9 LC) developed by us with 2 transfer learning models (Visual Geometry Group) 16 and VGG19. Two different datasets used in this study were obtained from the Kaggle database and the Radiodiagnosis department of our institution. Results In our study, VGG16 yields the highest accuracy among all three models for different datasets as the Kaggle dataset-94.96% and the department of Radiodiagnosis dataset 85.71%. Although, the precision was found better while using 9 LC and VGG19 for both datasets. Conclusions DL can help the radiologists in the speedy prediction of diseases and detecting minor features of the disease which may be missed by the human eye. In the present study, we have used three models, i.e.,, CNN with 9 LCs, VGG16, and VGG19 transfer learning models for the classification of X-ray images with good accuracy and precision. DL may play a key role in analyzing the medical image dataset.
Breast implant-associated anaplastic large-cell lymphoma (BIA-ALCL) is a malignancy associated with textured breast implants. BIA-ALCL is typically restricted to the periprosthetic capsule, ...presenting as a unilateral recurrent seroma years after placement of a textured breast implant. Current estimates suggest an incidence of one in 3300 for patients with Allergan Biocell textured implants. As of February 6, 2019, U.S. Medical Device Reporting associated with BIA-ALCL showed 457 unique cases of BIA-ALCL, with 24 "unverified and potentially inaccurate" cases associated with a nontextured implant. As of February of 2019, there were 688 reported cases to date worldwide. To date, there are no published case reports of BIA-ALCL associated exclusively with smooth implants or with smooth implants after textured expanders, and there has been no reported smooth-only case in any registry, database, or journal worldwide. The authors present a case of BIA-ALCL associated with smooth round implants and textured tissue expanders. A 56-year-old woman was treated for left stage IIA invasive ductal carcinoma with bilateral mastectomies and immediate reconstruction with bilateral subpectoral textured tissue expanders. She underwent exchange to Mentor smooth-round implants, and completed adjuvant chemotherapy. Magnetic resonance imaging and examination 4.5 years after implant placement showed no abnormal findings. The patient had left breast trauma 5 years following implant placement while taking adalimumab, and developed an open wound requiring explantation. A recurrent seroma developed, and tested positive for BIA-ALCL on cytology. Surgical pathologic examination after total capsulectomy demonstrated stage IA BIA-ALCL. To the authors' knowledge, this is the first case report of BIA-ALCL in a patient with textured expanders followed by prolonged exposure to smooth round implants.
This paper implements a wide aperture high-resolution true time delay for frequency-uniform beamforming gain in large-scale phased arrays. We propose a baseband discrete-time delay-compensating ...technique to augment the conventional phase-shift-based analog or hybrid beamformers. A generalized design methodology is first developed to compare delay-compensating analog or hybrid beamforming architecture with their digital counterpart for a given number of antenna elements, modulation bandwidth, ADC dynamic range, and delay resolution. This paper shows that delay-compensating analog or hybrid beamformers are more energy-efficient for high dynamic-range applications compared to true-time-delay digital beamformers. To demonstrate the feasibility of our proposed technique, a four-element analog delay-compensating baseband beamformer in 65-nm CMOS is prototyped. A time-interleaved switched-capacitor array implements the discrete-time delay-compensating beamformer with a wide delay range of 15-ns and 5-ps resolution. Measured power consumption is 47 mW with frequency-uniform array gain over 100-MHz modulated bandwidth, independent of angle of arrival. The proposed delay compensation scheme is scalable to accommodate the delay differences for large antenna arrays with higher range/resolution ENOB compared with prior art.
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