Nano Contact Research Articles

Comparative Analysis of Refractive Outcomes Using Optical and Ultrasound Biometry in Phacoemulsification Cataract Surgery

Background: Accurate biometry is critical for optimal visual outcomes in cataract surgery. Both optical and ultrasound biometry are widely used, but their comparative effectiveness remains under evaluation.Objective: To compare the refractive outcomes of optical and ultrasound biometry in patients undergoing elective phacoemulsification cataract surgery.Methods: This prospective cohort study included 352 patients aged 30-60 years undergoing elective phacoemulsification with in-the-bag IOL implantation. Patients were randomly assigned to either optical biometry using the Zeiss IOL Master 700 or ultrasound biometry with Axis Nano contact A-mode echography. Visual acuity and spherical equivalent were measured at baseline and 4 weeks post-operatively. Data were analyzed using SPSS version 25, with independent t-tests comparing outcomes between groups.Results: The mean post-operative visual acuity was 0.83 ± 0.22, with a mean spherical equivalent of -0.88 ± 0.16. No significant difference was found between the ultrasound (-0.89 ± 0.17) and optical biometry (-0.87 ± 0.16) groups (p=0.152, 95% CI -0.06 to 0.01).Conclusion: Both optical and ultrasound biometry provide comparable refractive outcomes in cataract surgery, with no significant difference in post-operative spherical equivalent.

Comparative evaluation on surface nanohardness, surface microhardness, surface roughness, and wettability of plant-based organic nanoparticle reinforced polyetheretherketone as an implant material - An in vitro study.

Synthetic inorganic materials are commonly used as reinforcing agents in polyetheretherketone (PEEK) composite, whereas natural organic plant-based reinforcing agents are negligible. Surface hardness, roughness, and wettability are indicative factors of osseointegration behavior to be used as an implant material. This study evaluated micro surface hardness (MSH), nano surface hardness (NSH), surface roughness (SR), and contact angle (CA) of PEEK-Azadirachta indica reinforced at 10 wt%, 20 wt%, and 30 wt%. This was an in vitro study. Neem (A. indica) leaf nanoparticles were prepared and reinforced with PEEK powder at 10%, 20%, and 30% weight ratios by injection molding. Sixty specimens underwent the microhardness and CA testing using a digital microhardness tester, and CA goniometer, respectively, and later nanoindentation test to analyze the nanohardness and SR. A one-way ANOVA test with a 95% confidence interval for MSH and NSH, SR, and CA was performed on the samples. A post hoc Bonferroni test was conducted (α = 0.05) to compare the groups. There was a significant increase in nanohardness (P = 0.000) with zero difference in microhardness (P = 0.514). The addition of 10 wt%, 20 wt%, and 30 wt% nanoparticles increased the SR value of the pure PEEK from 273.19 nm to 284.10 (3.99%), 296.91 (8.68%), and 287.54 (5.24%), respectively. In the analysis of the CA, CA 20% shows the lowest angle (63.69) with the highest for control specimens (82.39). There is an increase in the PEEK composite SR with a decrease in CA. The addition of plant-derived nanoparticles into the PEEK matrix has a significant impact on the hardness and hydrophobicity enhancing cell growth and osteoblastic differentiation during osseointegration of dental implants.

Evaluating nano-metal oxide mixed matrix membranes for whey protein separation using hybrid intelligent optimization learning

Ultrafiltration (UF) membranes offer cost-efficient and sustainable techniques for the extraction of whey protein in cheese whey wastewater. This strategy substantially aids in waste minimization and fosters the progression of a circular economy paradigm within the dairy industry. The emerging discipline of machine learning has benefited UF by enhancing the separation performance and deepening the filtration mechanism. In this study, adaptive neuro-fuzzy inference systems (ANFIS) coupled chemometric learning was implemented for the performance evaluation of whey protein recovery in nano metal oxide embedded mixed matrix membranes (MMMs) UF from whey wastewater. The selected input variables are nano metal oxides concentration (NC), pore radius (S), and contact angle (CA). The targeted responses for the parametric dependency analysis are individual whey protein permeability (lysozyme (PLys), lactalbumin (PLA) and bovine serum albumin (PBSA)) and protein rejection (%) (lysozyme (RLys), lactalbumin (RLA) and bovine serum albumin (RBSA)). The Jarque-Bera indicated that the input variables did not deviate from normality, and S and CA have significantly influenced the whey protein rejection and permeability. ANFIS models demonstrate superior predictive capabilities with minimal error for flux under various transmembrane pressure (TMP) in MMMs due to their inherent gradient descent optimization. Among the proteins, a Pearson correlation coefficient approaching unity denotes a significant positive relationship between lysozyme flux (FLys). The ANFIS models exhibited excellent predictive performance in real-time cheese whey effluent flux and rejection data, achieving a mean square error of 0.0003 for experimental flux. This study provides valuable insights for the development of models tailored to small datasets, offering a foundation for predicting and enhancing membrane performance.

Microstructure, mechanical properties and high temperature corrosion of [AlTiCrNiTa/(AlTiCrNiTa)N]20 high entropy alloy multilayer coatings for nuclear fuel cladding

[AlTiCrNiTa/(AlTiCrNiTa)N]20 multilayer coatings were prepared by magnetron sputtering on Zr-4 substrate. The mechanical properties, microstructure and wettability of multilayer coatings were systematically studied by SEM, nano indentation instrument, scratch instrument and contact Angle instrument. In addition, after high temperature oxidation corrosion for 45 days, the coating was characterized by SEM and XRD. Al in the coating was wrapped in dense spinel NiCr2O4, which inhibits layer by layer dissolution of the coating, thus improving the corrosion resistance of the coating. The corrosion mechanism of [AlTiCrNiTa/(AlTiCrNiTa)N]20 multilayer coatings was evaluated in detail.

PeakForce Quantitative Nanomechanical Imaging for Characterization of the Surface Energy of Nano-Patterned Au Strip

ABSTRACT Precise measurement of the surface energy of nanoscale metal thin films is crucial for the fabrication of reliable miniaturized electronic devices consisting of multi-stacked thin film strips. However, the conventional method utilizing sessile drops to measure the surface energy is not suitable for nanoscale samples owing to the much larger size of the liquid droplets than those of the samples being measured. Herein, nCA-AFM (nano contact angle-atomic force microscopy) based on PF-QNM (PeakForce quantitative nanomechanical mapping) imaging mode is explored as a novel tool to measure the surface energy of nanoscale Au strips. Au strips with thicknesses of 50 and 100 nm were patterned to have widths in a range from 200 to 500 nm. The surface energy of the nano-patterned Au strips measured with PF-QNM methods revealed that grain size is the most important factor determining the surface energy. The sample having different widths with the same grain size showed similar surface energy values, regardless of the sample dimensions. Our results highlight that grain size control is required to achieve the target surface energy of metal strips for applications in nanoscale electronic devices.

Enhanced spin wave coupling between array of spin torque nano oscillators in magnonic crystal cavities

Spin wave coupling between nano contact spin torque nano oscllators in asymmetric and symmetric array of antidot MC cavities to obtain sustained spin wave oscillations using supercell plane wave method and micromagnetics is discussed. The SWs were excited by injecting a spin-polarized current into a single nano contact in a L3 magnonic crystal cavity(MCC) and radiate like an end-fire antenna. The SW oscillations are then coupled into one of the guided modes of a magnonic crystal waveguide (MCW). The MCC acts as a SW resonator and spin-torque injection as gain. Together they achieve sustainable oscillations in a manner analogous to the behavior of a laser cavity. The phase locking of arrays of cavities arranged symmetrically and asymmetrically on both sides of a MCW is also discussed. Spin waves are radiated like a broadside antenna. The PSD of the broadside case is 28 dB lower than that of the end-fire case. The obtained value from the micromagnetic simulation is used to find the corresponding point in the guided mode of MCW, and this occurs nearer to the edge of the Brillouin zone. We also investigated the point in dispersion where the maximum energy is coupled from MCC to MCW. The spectral characteristics of the broadside coupling were correlated with frequency pulling effects in the laser cavity. Asymmetric spin-torque excitations on either sides of the MCW cause odd frequency peaks in the PSD characteristics. This can be mitigated when we use MC cavities placed symmetrically on both sides of the MCW, and excite spin waves in each cavity. However, spin waves excited in an asymmetric array of cavities add in phase, yielding a power enhancement with an increase in the number of cavities. Spin waves excited in a symmetric array of cavities add out of phase and result in spin-wave decoherence with an increase in the number of cavities.

Societal factors affecting on innovative sustainable development of nanotechnology: a morphological approach

PurposeThis study aims to investigate the probable future scenarios of nanotechnology development and their implications in Iran considering anticipatory knowledge, suitable methodology and integral perspective.Design/methodology/approachThe study used framework morphology, a method for creating scenarios and their implications developed by the Delphi method that covers the consistent morphological space and make contact with previous scenario work, as well as the current and projected research and policy situation in Iran.FindingsThe study identified five scenarios, namely, “no nano” scenario headlines picturing a future society that there is no impact of nanotechnology in it. The “nano flow” scenario and indicates prospering nanotechnology in the full sides of the market. The “no nano contact” scenario suspecting that apart from the already banned nanotechnological applications in food, cosmetics, clothes and agricultural applications might bear equally unacceptable risks. The “hidden nano” scenario by pointing out the effects of accidents and crimes traced back to intended or unintended misuse of nanotechnological applications. Then finally, the “red nano” scenario illustration headlines the prospects of medical, energy system efficiency and nanotechnological applications in information and communication technologies.Practical implicationsThe policymakers could use the scenarios and their implications as part of its considerations in strategic planning.Originality/valueThis paper represents the first time that a framework for societal implications has been applied to nanotechnology development topic in Iran.

Novel bimetallic nano particles for sorption of mercury (II) from drinking water: Adsorption experiment and computational studies

The current study proposes fabrication of novel manganese and copper (Mn/Cu) based bimetallic nano particles (NPs) for adsorptive removal of mercury (Hg) ions from aqueous media and examines computational models for adsorption. The Mn/Cu bimetallic NPs were characterized for Atomic Force Microscope (AFM), Energy Dispersive X-rays Spectroscopy (EDS), X-Ray Diffraction (XRD) and Dynamic Light Scattering (DLS) techniques to investigate morphology, surface elemental composition and particle size analysis. Sorption of Hg was carried out using batch experiments in triplicate and residual Hg concentration after sorption was determined using cold vapor atomic absorption spectrometer (CV-AAS). The effect of various parameters such as pH, mass of nano particles, Hg concentration and contact time were optimized. Maximum removal efficiency was 95 % with 2.89 % RSD and maximum adsorption capacity (Q max) observed was 400 mg g-1. AFM images well separated morphology and mean grain size of 450 ± 50 nm of particles, DLS measured average particles size as 110 nm while XRD pattern and EDS results showed successful adsorption of Hg on Mn/Cu bimetallic surface. Ab initio based computational models for different geometries were optimized using semi empirical method through Gaussian software. Computational molecular models were optimized for structures before and after Hg sorption and important physical parameters such as electron spin, Root mean square (RMS) gradient, Adsorption energy, Mulliken charge density (Q) and bond lengths (BL) before and after adsorption were computed. It was concluded that Langmuir adsorption isotherm was favorable for this study and interaction of Hg was more favorable with Mn than Cu because of less adsorption energy (-112.48 eV) and stronger bond formation between them having bond length of 1.6433 Å.

Time-resolved imaging of magnetization dynamics in double nanocontact spin torque vortex oscillator devices

Double nanocontact (NC) spin transfer vortex oscillator devices, in which NCs of 100-nm diameter have center-to-center separation ranging from 200 to 1100 nm, have been studied by means of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM). The NCs were positioned close to the edge of the top electrical contact so that the magnetization dynamics of the adjacent region could be probed optically. The electrical measurements showed different ranges of frequency operation for devices with different NC separations. For 900-nm NC separation, TRSKM showed magnetic contrast consistent with the formation of a magnetic vortex at each NC, while for 200-nm NC separation a lack of magnetic contrast near the NC region suggests that the magnetization dynamics occur closer to the NC and underneath the top contact. TRSKM also reveals the presence of additional localized dynamical features far from the NCs, which are not seen by electrical measurements; has not been reported previously for double NCs with different separations; and provides insight into how the dynamic state of the phase-locked oscillators is established and stabilized.

Effects of Typical Physical Properties on Tribological Behaviors of Three Kinds of Polymer Materials for Water-Lubricated Bearings

The stretching, shearing, deformation, peeling, and temperature rise phenomena at the micro–nano contact interface have a great influence on its tribological properties and significantly affect the service life of key moving parts made of polymers. The physical properties of the three typical polymer materials used for ship bearing polymer materials (ultra-high-molecular-weight polyethylene, synthetic rubber, and polypropylene) were examined to investigate their effects on the wear behaviors. The results showed that synthetic rubber has good wear resistance because of its excellent shear strength, tensile strength, and high initial thermoplastic deformation temperature. Low initial thermoplastic deformation temperature resulted in great wear to the polypropylene material under dry friction, whereas its good wettability resulted in good wear resistance under water-lubricated condition. The ultra-high-molecular-weight polyethylene had the poorest wear resistance under water-lubricated condition because it had the poorest shear strength and tensile strength. The knowledge gained herein provides a better understanding of the relationships between the physical behaviors of polymer materials and their friction and wear mechanisms, along with guidance for selecting and designing polymer friction pairs for ship bearings.

Optimization of biosorption potential of nano biomass derived from walnut shell for the removal of Malachite Green from liquids solution: Experimental design approaches

Activated carbon based on walnut shell as a biomass material was synthesized and successfully applied for the removal of malachite green (MG) from aqueous solution. Fourier transform infrared spectroscopy, Transmission electron microscopy, Brunauer–Emmett–Teller, Dynamic light scattering and X-ray diffraction were used to characterize the biomass. In batch study, response surface methodology was utilized to screen and optimize key operating parameters with considering removal efficiency as a response. Central composite design was applied to indicate the influence of operating variables including initial concentration of MG (16.5–33.5 mg L−1), nano biomass dose (16.5–33.4 mg) and contact time (13.0–47.0 min) on MG uptake from the aqueous solution. Obtained results showed that about 100% elimination was attained at initial MG concentration of 33.3 mg L−1, nano biomass dose of 33.3 mg and contact time of 20.0 min.Data analysis was done by different adsorption isotherms such as Langmuir, Temkin, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) and the results introduced Langmuir isotherm as a suitable model to define the adsorption behaviors. Finally, the pseudo second order kinetic model described the MG sorption process with a well-fitting (R2 = 0.9897).

Synthesis, Characterization of α-Al2O3 Nanoparticles and Its Application in Decolorization of Methyl Orange Azo Dye in the Presence of UV Light

Present study deals with the sol-gel synthesis and application of α-Al2O3 nanoparticles (alumina) to decolorize the azo anionic dye methyl orange (MO). α-Al2O3 nanoparticles were successfully synthesized using aluminium oxide, 25% ammonia and polyvinyl alcohol (PVA) were used as low cost raw materials. The properties of synthesized nanoparticles were investigated by using UV-visible spectroscopy, XRD, FTIR, SEM, EDAX, Raman spectroscopy and TEM. From UV–visible spectra, band gap was calculated and it was found to be 3.31 eV. Average crystal size of α-Al2O3 nanoparticles from XRD peaks found to be 25 nm having rhombohedral structure. FTIR spectra reveals that functional groups (O-Al-O) are present. SEM image shows distribution pattern of α-Al2O3 nanoparticles. Chemical composition of α-Al2O3 nanoparticles was confirmed from EDAX spectroscopy measurement. Raman spectra showed crystalline nature of α-Al2O3 nanoparticles. The effect of concentration and pH of dye, dosage of nano adsorbent and contact time were studied. The systematic study shows that, successful color removal of methyl orange dye up to 54% in three hours contact time of pH 4. Hence α-Al2O3 nanoparticles can be used for dye removal from waste water. Industrialization of this technique will be cost effective way to decolorize the textile dye present in water system.

Nano and microscale contact characteristics of tribofilms derived from fully formulated engine oil

A systematic approach is required in order to determine the frictional characteristics of a contacting pair in the presence of a tribofilm. Despite the clear benefits in functionality and in reducing wear, the generation of ZDDP-based tribofilms often lead to increased frictional losses. Such an increase is also observed in the tribometric tests reported here, as well as in open literature. This paper investigates the underlying mechanics for the rise in friction using an integrated methodology, based upon Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The use of an analytical contact mechanics model demonstrates that the pressure coefficient of boundary shear strength, measured using lateral force microscopy, provides an explanation for the observed increase in measured friction at micro-scale.

Time resolved imaging of the non-linear bullet mode within an injection-locked nano-contact spin Hall nano-oscillator

Time-resolved scanning Kerr microscopy (TRSKM) has been used to image precessional magnetization dynamics excited by a DC current within a nano-contact (NC) spin Hall nano-oscillator (SHNO). Injection of a radio frequency (RF) current was used to phase lock the SHNO to TRSKM. The out of plane magnetization was detected by means of the polar magneto optical Kerr effect (MOKE). However, longitudinal MOKE images were dominated by an artifact arising from the edges of the Au NCs. Time resolved imaging revealed the simultaneous excitation of a non-linear “bullet” mode at the centre of the device, once the DC current exceeded a threshold value, and ferromagnetic resonance (FMR) induced by the RF current. However, the FMR response observed for sub-critical DC current values exhibits an amplitude minimum at the centre, which is attributed to spreading of the RF spin current due to the reactance of the device structure. This FMR response can be subtracted to yield images of the bullet mode. As the DC current is increased above threshold, the bullet mode appears to increase in size, suggesting increased translational motion. The reduced spatial overlap of the bullet and FMR modes, and this putative translational motion, may impede the injection locking and contribute to the reduced locking range observed within NC-SHNO devices. This illustrates a more general need to control the geometry of an injection-locked oscillator so that the autonomous dynamics of the oscillator exhibit strong spatial overlap with those resulting from the injected signal.

Investigation of magnetic droplet solitons using x-ray holography with extended references

A dissipative magnetic soliton, or magnetic droplet, is a structure that has been predicted to exist within a thin magnetic layer when non-linearity is balanced by dispersion, and a driving force counteracts the inherent damping of the spin precession. Such a soliton can be formed beneath a nano-contact (NC) that delivers a large spin-polarized current density into a magnetic layer with perpendicular magnetic anisotropy. Although the existence of droplets has been confirmed from electrical measurements and by micromagnetic simulations, only a few attempts have been made to directly observe the magnetic landscape that sustains these structures, and then only for a restricted set of experimental parameter values. In this work we use and x-ray holography technique HERALDO, to image the magnetic structure of the [Co/Ni]x4 multilayer within a NC orthogonal pseudo spin-valve, for different range of magnetic fields and injected electric currents. The magnetic configuration imaged at −33 mA and 0.3 T for devices with 90 nm NC diameter reveals a structure that is within the range of current where the droplet soliton exist based on our electrical measurements and have it is consistent with the expected size of the droplet (∼100 nm diameter) and its spatial position within the sample. We also report the magnetisation configurations observed at lower DC currents in the presence of fields (0–50 mT), where it is expected to observe regimes of the unstable droplet formation.

Designing magnetic droplet soliton nucleation employing spin polarizer

We show by means of micromagnetic simulations that spin polarizer in nano-contact (NC) spin torque oscillators as the representative of the fixed layer in an orthogonal pseudo-spin valve can be employed to design and to control magnetic droplet soliton nucleation and dynamics. We found that using a tilted spin polarizer layer decreases the droplet nucleation time which is more suitable for high speed applications. However, a tilted spin polarizer increases the nucleation current and decreases the frequency stability of the droplet. Additionally, by driving the magnetization inhomogenously at the NC region, it is found that a tilted spin polarizer reduces the precession angle of the droplet and through an interplay with the Oersted field of the DC current, it breaks the spatial symmetry of the droplet profile. Our findings explore fundamental insight into nano-scale magnetic droplet soliton dynamics with potential tunability parameters for future microwave electronics.

Resonant spin wave excitations in a magnonic crystal cavity

Spin polarized electric current, injected into permalloy (Py) through a nano contact, exerts a torque on the magnetization. The spin waves (SWs) thus excited propagate radially outward. We propose an antidot magnonic crystal (MC) with a three-hole defect (L3) around the nano contact, designed so that the frequency of the excited SWs, lies in the band gap of the MC. L3 thus acts as a resonant SW cavity. The energy in this magnonic crystal cavity can be tapped by an adjacent MC waveguide (MCW). An analysis of the simulated micromagnetic power spectrum, at the output port of the MCW reveals stable SW oscillations. The quality factor of the device, calculated using the decay method, was estimated as Q>105 for an injected spin current density of 7×1012A/m2.

비등 열전달 시스템의 안정성 향상을 위한 탄소나노튜브 코팅의 열전달 및 내구성에 대한 연구

In this study, we investigated to the heat transfer performance of coating nano-structure with various shapes and patterns on the heat transfer surface. As a result of the measurement of the 3D nano shape, it was confirmed that the roughness generally increases when the adhesive is sprayed on the coating surface and finished durability experiment. In the case of TEOS adhesive, the roughness increased by <TEX>$0.074{\mu}m$</TEX>, <TEX>$0.012{\mu}m$</TEX> and <TEX>$0.015{\mu}m$</TEX>, and the contact angle decreased <TEX>$12.64^{\circ}$</TEX>, <TEX>$1.31^{\circ}$</TEX>, <TEX>$9.84^{\circ}$</TEX> at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of PVA adhesive, the roughness increased by <TEX>$0.069{\mu}m$</TEX>, <TEX>$0.056{\mu}m$</TEX> and <TEX>$0.03{\mu}m$</TEX>, and the contact angle decreased <TEX>$2.85^{\circ}$</TEX>, <TEX>$4.82^{\circ}$</TEX>, <TEX>$6.96^{\circ}$</TEX> at the coating time of 120 seconds, 180 seconds and 240 seconds, respectively. In the case of DGEBF adhesive, the roughness increased by <TEX>$0.042{\mu}m$</TEX>, <TEX>$0.053{\mu}m$</TEX> and <TEX>$0{\mu}m$</TEX>, and the contact angle decreased <TEX>$0.81^{\circ}$</TEX> at the coating time of 120 seconds, increased <TEX>$4.82^{\circ}$</TEX>, <TEX>$6.96^{\circ}$</TEX> at the coating time of 180 seconds and 240 seconds, respectively. As a result, the durability tends to decrease as more nano-structures are deposited, and 3D nano shapes, contact angles and SEM photographs showed that the performance of the PVA adhesive was superior among the three adhesives.

Superharmonic injection locking of nanocontact spin-torque vortex oscillators

Super-harmonic injection locking of single nano-contact (NC) spin-torque vortex oscillators (STVOs) subject to a small microwave current has been explored. Frequency locking was observed up to the fourth harmonic of the STVO fundamental frequency $f_{0}$ in microwave magneto-electronic measurements. The large frequency tunability of the STVO with respect to $f_{0}$ allowed the device to be locked to multiple sub-harmonics of the microwave frequency $f_{RF}$, or to the same sub-harmonic over a wide range of $f_{RF}$ by tuning the DC current. In general, analysis of the locking range, linewidth, and amplitude showed that the locking efficiency decreased as the harmonic number increased, as expected for harmonic synchronization of a non-linear oscillator. Time-resolved scanning Kerr microscopy (TRSKM) revealed significant differences in the spatial character of the magnetization dynamics of states locked to the fundamental and harmonic frequencies, suggesting significant differences in the core trajectories within the same device. Super-harmonic injection locking of a NC-STVO may open up possibilities for devices such as nanoscale frequency dividers, while differences in the core trajectory may allow mutual synchronisation to be achieved in multi-oscillator networks by tuning the spatial character of the dynamics within shared magnetic layers.

Direct observation of magnetization dynamics generated by nanocontact spin-torque vortex oscillators

Time-resolved scanning Kerr microscopy has been used to directly image the magnetization dynamics of nano-contact (NC) spin-torque vortex oscillators (STVOs) when phase-locked to an injected microwave (RF) current. The Kerr images reveal free layer magnetization dynamics that extend outside the NC footprint, where they cannot be detected electrically, but which are crucial to phase-lock STVOs that share common magnetic layers. For a single NC, dynamics were observed not only when the STVO frequency was fully locked to that of the RF current, but also for a partially locked state characterized by periodic changes in the core trajectory at the RF frequency. For a pair of NCs, images reveal the spatial character of dynamics that electrical measurements show to have enhanced amplitude and reduced linewidth. Insight gained from these images may improve understanding of the conditions required for mutual phase-locking of multiple STVOs, and hence enhanced microwave power emission.