The surface roughness is an important parameter in determining the physical properties and quality of thin films deposited by physical vapor deposition (PVD) method. The presence of an intermediate ...layer between metallic nanoparticles and substrate significantly promotes the adhesion and reduces the surface roughness. In this article, we have investigated the effect of Chromium (Cr) seed layer to optimize the surface roughness on the growth of as-deposited silver (Ag) film using borosilicate glass and silicon wafer substrates. For this purpose, Ag thin films were deposited with a Cr seed layer of different thickness on borosilicate glass and silicon wafer substrates using an electron beam (E-Beam) deposition method. The Cr thin film of different thickness ranging from 1 nm to 6 nm was thermally evaporated and pure Ag with the same thickness was evaporated at the same rate on previously coated substrates. The deposition of the nanostructured thin film was confirmed by UV-Vis and XRD characterizations. The difference in transmittance for uncoated and coated substrates ensured the deposition. The presence of pure Ag crystalline phase was confirmed by XRD pattern. Surface roughness was measured using Atomic Force Microscopy (AFM) and the conductance was measured using 4-probe conductivity method. The density of nanoparticles and smoothness were visualized from two dimensional (2D) and three dimensional (3D) surface height histograms of representative AFM images. The quantitative roughness was measured in terms of root mean square (RMS) roughness and mean roughness. The high dense and smoother thin films were found for ~2-4 nm Cr layer thickness in case of the glass substrate. The slight increase in roughness was observed for ~1-6 nm Cr layer thickness in case of the silicon substrate. The dependence of the conductivity of thin films on surface roughness is investigated to verify the effect of surface roughness on different applications of Ag thin film. The conductance results have been analyzed as; for a glass substrate, conductivity was maximum for thin films containing ~2 nm Cr seed layer thickness, while for silicon substrate the maximum conductivity was found for the thin film containing ~1 nm Cr seed layer.
Fast entangling gates in long ion chains Mehdi, Zain; Ratcliffe, Alexander K.; Hope, Joseph J.
Physical review research,
01/2021, Letnik:
3, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We present a model for implementing fast entangling gates (∼1μs) with ultrafast pulses in arbitrarily long ion chains, that requires low numbers of pulses and can be implemented with laser repetition ...rates well within experimental capability. We demonstrate that we are able to optimize pulse sequences that have theoretical fidelities above 99.99% in arbitrarily long ion chains, for laser repetition rates on the order of 100–300 MHz. Notably, we find higher repetition rates are not required for gates in longer ion chains, which is in contrast to scaling analyses with other gate schemes. When pulse imperfections are considered in our calculations, we find that achievable gate fidelity is independent of the number of ions in the chain. We also show that pulse control requirements do not scale up with the number of ions. We find that population transfer efficiencies of above 99.9% from individual ultrafast pulses is the threshold for realizing high-fidelity gates, which may be achievable in near-future experiments.
Intracranial blister aneurysms are a rare and an historically difficult to treat subset of aneurysms. They are distinct from typical saccular aneurysms with different pathophysiology and treatment ...options.
A prospectively maintained database of subarachnoid hemorrhage patients was queried for those presenting prior to the pandemic (2017–2019), and those presenting during the height of the pandemic in our locality (2021). Aneurysm characteristics and patient demographics associated with rupture risk/formation were collected.
334 aneurysmal subarachnoid hemorrhage patients were reviewed. 86 of these patients presented in 2021, with a statistically significant increase in the proportion of ruptured ICA blister aneurysms as compared to 2017–2019 (7/86, 8% vs 5/248, p = .02). Mean patient age, presenting grade, other aneurysm location proportions, aneurysm size, and incidence of delayed cerebral ischemia were not different between the groups.
Patients presenting with SAH during the height of the SARS-CoV-2 pandemic in 2021 were more likely to have ICA blister type aneurysms.
•Patients presenting during the height of the COVID-19 pandemic were more likely to have blister type aneurysms.•Presenting Hunt and Hess grade was not different pre and post pandemic.•Incidence of delayed cerebral ischemia was not different pre and post pancdemic.
Dissipation of quantum vortex motion is fundamental to superfluid dynamics and quantum turbulence, yet there is currently a large gap between theory and experiments with ultracold atoms. Here we ...present a microscopic open quantum systems theory of thermally damped vortex motion in oblate atomic superfluids that includes previously neglected energy-damping interactions between superfluid and thermal atoms. This mechanism couples strongly to vortex core motion and causes dissipation of vortex energy due to mutual friction, as well as Brownian motion of vortices due to thermal fluctuations. We derive an analytic expression for the dimensionless mutual friction coefficient that gives excellent quantitative agreement with experimentally measured values, without any fitted parameters. Our work closes an existing two orders of magnitude gap between dissipation theory and experiments, previously bridged by fitted parameters, and provides a microscopic origin for the mutual friction and diffusion of quantized vortices in two-dimensional atomic superfluids.
During emergencies LTE/5G-based public mobile land networks (PLMNs) restrict network access by normal users, which means a lack of service reliability which limits application of LTE/5G for ...machine-type communication (MTC) in critical applications, such as power systems This paper shows how existing LTE/5G features can be used to differentiate MTC of devices in a microgrid from other MTC or human-to-human (H2H) communication and ensure that these microgrid devices have service during emergencies, which enables use of LTE/5G communication to co-ordinate the use of distributed energy resources (DER) in microgrids, so that they can autarkically perform blackout recovery of an islanded microgrid. It is shown that this method allows the blackout recovery 100 times faster than with a conventional black start. The microgrid blackout recovery is demonstrated using the LTE/5G PLMN Access Barring feature. The disadvantage of using PLMN-based Access Barring is the need to define two separate PLMNs in one radio cell, which is an inefficient use of radio spectrum. However, this can be avoided by using the Extended Access Class Barring (EAB) override or application-specific congestion control (ACDC) features of the CAT-M1 low-power wide-area MTC technology, which are included in LTE and 5G standards.
Multi-walled carbon nanotubes (MWCNTs) grown by chemical vapor deposition (CVD), which are commercially available in large quantities, commonly show poor field emission characteristics due to their ...low crystallinity. In this study, we fabricated highly crystalline MWCNTs using arc discharge (AD) via a mixture of N2 and O2 gases. The AD-MWCNTs showed a high oxidation temperature and lower threshold (Vth) and turn-on (Vto) voltages in repeated field emission measurements compared to CVD-MWCNTs. In a lifetime evaluation performed at an anode current of 3 mA for 20 and 120 h in diode and triode configurations, respectively, AD-MWCNTs showed better long-term stability than the CVD-MWCNTs. Thus, our findings demonstrate that AD-MWCNTs are promising for use in high-performance field emitters.
Mobility by growth is a new paradigm in robotic systems design and their applications in the real world. Soft, tip-extending, or "growing", robots have potential applications including inspection and ...navigation in disaster scenarios. However, due to their growing capability, such robots create unique challenges for intuitive human control. In this paper, a new flexible interface is proposed to intuitively map human bending commands into movements of the growing robot while providing shape information of the robot in order to improve situational awareness. Several command mappings are proposed, and a subjective study was conducted to assess the intuitiveness of the developed interface and mappings compared with other commercially available interfaces. The interfaces were evaluated using four metrics in two virtual task scenarios. The proposed interface with shape mapping performed better than the other interfaces, especially when the vine robot rolls over unintentionally during complex tasks.
Summary
We explored the potential of heteroatom‐doped graphene oxide (GO)‐based electrodes for energy storage. Binder‐free electrodes were synthesized using the hydrothermal method, where doping of ...GO and its electrode development was achieved simultaneously in one step. GO was doped with nitrogen (NGO) and boron (BGO) using urea and boric acid as nitrogen (N) and boron (B) sources, respectively. In addition, GO was also co‐doped with B and N (BNGO). The atomic percentages of nitrogen and boron in NGO and BGO were found out to be 6.13% and 17.94%, respectively, as revealed by XPS. The BNGO had atomic percentages of boron and nitrogen as 23.76% and 3.64%, respectively. Electrodes were electrochemically characterized in 3 M KOH electrolyte by employing cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge‐discharge (GCD). CV analysis revealed that NGO and BNGO exhibited superior charge storage capacity with a high specific capacitance of 855 and 811 F g−1, respectively, at 1 m Vs−1. CV data were further analyzed to identify and quantify charge storage mechanism, and it suggested that binder‐free‐doped electrodes exhibited diffusion‐controlled charge storage as dominant behavior. Thus, our results demonstrate an approach to dope GO and develop high‐performance, binder‐free electrodes for supercapacitor applications in a facile single‐step hydrothermal method.
Facile single‐step binder‐free synthesis of GO using hydrothermal process.
Investigate the effect of heteroatom doping of GO on capacitive behavior.
Nitrogen‐doped (N‐)G0 exhibited superior charge storage capacity with a high specific capacitance of 855 at 1 m Vs−1.
The surface roughness is an important parameter in determining the physical properties and quality of thin films deposited by physical vapor deposition (PVD) method. The presence of an intermediate ...layer between metallic nanoparticles and substrate significantly promotes the adhesion and reduces the surface roughness. In this article, we have investigated the effect of Chromium (Cr) seed layer to optimize the surface roughness on the growth of as-deposited silver (Ag) film using borosilicate glass and silicon wafer substrates. For this purpose, Ag thin films were deposited with a Cr seed layer of different thickness on borosilicate glass and silicon wafer substrates using an electron beam (E-Beam) deposition method. The Cr thin film of different thickness ranging from 1 nm to 6 nm was thermally evaporated and pure Ag with the same thickness was evaporated at the same rate on previously coated substrates. The deposition of the nanostructured thin film was confirmed by UV-Vis and XRD characterizations. The difference in transmittance for uncoated and coated substrates ensured the deposition. The presence of pure Ag crystalline phase was confirmed by XRD pattern. Surface roughness was measured using Atomic Force Microscopy (AFM) and the conductance was measured using 4-probe conductivity method. The density of nanoparticles and smoothness were visualized from two dimensional (2D) and three dimensional (3D) surface height histograms of representative AFM images. The quantitative roughness was measured in terms of root mean square (RMS) roughness and mean roughness. The high dense and smoother thin films were found for ~2-4 nm Cr layer thickness in case of the glass substrate. The slight increase in roughness was observed for ~1-6 nm Cr layer thickness in case of the silicon substrate. The dependence of the conductivity of thin films on surface roughness is investigated to verify the effect of surface roughness on different applications of Ag thin film. The conductance results have been analyzed as; for a glass substrate, conductivity was maximum for thin films containing ~2 nm Cr seed layer thickness, while for silicon substrate the maximum conductivity was found for the thin film containing ~1 nm Cr seed layer.
PDF
