Multi-antenna relay network beamforming design for multiuser peer-to-peer communications.

In this work, we consider a multi-user peer-to-peer relay network with multiple multiantenna relays which employ amplify-and-forward relaying protocol. Assuming distributed relay beamforming strategy, we investigate the design of each relay processing matrix to minimize the per-antenna relay power usage for given users??? Signal-to-Noise Ratio (SNR) targets. As the problem is NP-hard, we develop an approximate solution through the Lagrange dual domain. Through a sequence of transformations, we obtain a semi-closed form solution which can be determined by solving an efficient semi-definite programming problem. We also consider the semi-definite relaxation (SDR) approach. Compared with this SDR approach, the proposed solution has significantly lower computational complexity. The benefit of such a solution is apparent when the optimal solution can be obtained by both approaches. When the solution is suboptimal, simulations show that the SDR approach has better performance. Thus, we propose a combined method of the two approaches to trade-off performance and complexity. Simulations showed the effectiveness of such a combined method. In the next step, we change the previous objective and constraints to turn the optimization problem into a total power minimization problem for the relay network. We use an approximation by solving this problem in the Lagrange dual domain, and we finally obtain a semi-closed form solution through the dual approach. The use of the SDR approach to solve this problem is also discussed. After analysis, we find the two methods have an advantage over different aspects, thus we propose a combined method for this problem. We eventually compare the two combined methods to see the performance difference in the per-antenna power case and the total relay power case, and discuss reasons for this difference

Enhanced temperature sensing by multi-mode coupling in an on-chip microcavity system

The micro-cavity is a promising sensor platform, any perturbation would disturb its linewidth, cause resonance shift or splitting. However, such sensing resolution is limited by the cavity's optical quality factor and mode volume. Here we propose and demonstrate in an on-chip integrated microcavity system that resolution of a self referenced sensor could be enhanced with multi mode coupling

Structural and electronic properties of the metal-metal intramolecular junctions of single-walled carbon nanotubes

Several intramolecular junctions (IMJs) connecting two metallic (11, 8) and (9, 6) carbon nanotubes along their common axis have been realized by using a layer-divided technique to the nanotubes and introducing the topological defects. Atomic structure of each IMJ configuration is optimized with a combination of density-functional theory (DFT) and the universal force field (UFF) method, based upon which a four-orbital tight-binding calculation is made on its electronic properties. Different topological defect structures and their distributions on the IMJ interfaces have been found, showing decisive effects on the localized density of states, while the sigma-pi coupling effect is negligible near Fermi energy (EF). Finally, a new IMJ model has been proposed, which probably reflects a real atomic structure of the M-M IMJ observed in the experiment [Science 291, 97 (2001)].Comment: 11 pages and 3 figure

A tunable plasmonic refractive index sensor with nanoring-strip graphene arrays

In this paper, a tunable plasmonic refractive index sensor with nanoring-strip graphene arrays is numerically investigated by the finite difference time domain (FDTD) method. The simulation results exhibit that by changing the sensing medium refractive index nmed of the structure, the sensing range of the system is large. By changing the doping level ng, we noticed that the transmission characteristics can be adjusted flexibly. The resonance wavelength remains entirely the same and the transmission dip enhancement over a big range of incidence angles [0,45] for both TM and TE polarizations, which indicates that the resonance of the graphene nanoring-strip arrays is insensitive to angle polarization. The above results are undoubtedly a new way to realize various tunable plasmon devices, and may have a great application prospect in biosensing, detection and imaging

Meta-analysis of MMP-9 levels in the serum of patients with epilepsy

BackgroundEpilepsy’s pathogenesis and progression are significantly influenced by neuroinflammation, blood–brain barrier function, and synaptic remodeling function. Matrix metalloproteinase 9 (MMP-9), as a critical factor, may contribute to the development of epilepsy through one or more of the above-mentioned pathways. This study aims to evaluate and quantify the correlation between MMP-9 levels and epilepsy.MethodsWe conducted a comprehensive search of Embase, Web of Science, PubMed, Cochrane Library, WanFang DATA, VIP, and the CNKI to identify studies that investigate the potential association between MMP-9 and epilepsy. The data were independently extracted by two researchers and assessed for quality using the Cochrane Collaboration tool. The extracted data were analyzed using Stata 15 and Review Manager 5.4. The study protocol was registered prospectively at PROSPERO, ID: CRD42023468493.ResultsThirteen studies with a total of 756 patients and 611 matched controls met the inclusion criteria. Eight of these studies reported total serum MMP-9 levels, and the other five studies were used for a further subgroup analysis. The meta-analysis indicated that the serum MMP-9 level was higher in epilepsy patients (SMD = 4.18, 95% confidence interval = 2.18–6.17, p < 0.00001) compared with that in the control group. Publication bias was not detected according to Begg’s test. The subgroup analysis of country indicated that the epilepsy patients in China, Poland, and Egypt had higher levels of serum MMP-9 than the control group, with the increase being more pronounced in Egypt. The subgroup analysis of the age category demonstrated that the serum MMP-9 levels of the adult patients with epilepsy were significantly higher than those of the matched controls. However, the serum MMP-9 levels did not significantly differ in children with epilepsy. The subgroup analysis of the seizure types demonstrated substantial difference in the MMP-9 levels between patients of seizure-free epilepsy (patients who have been seizure-free for at least 7 days) and the control group. Meanwhile, the serum MMP-9 level in patients with epileptic seizures was significantly higher than that in the control group. The subgroup analysis based on seizure duration in patients showed that the serum MMP-9 levels at 1–3, 24, and 72 h after seizure did not exhibit significant differences between female and male patients with epilepsy when compared with the control group. The serum MMP-9 levels at 1–3 and 24 h were significantly higher than those of the matched controls. Nevertheless, the serum MMP-9 level at 72 h was not significantly different from that in the control group.ConclusionThis meta-analysis presents the first comprehensive summary of the connection between serum MMP-9 level and epilepsy. The MMP-9 levels in epilepsy patients are elevated. Large-scale studies with a high level of evidence are necessary to determine the exact relationship between MMP-9 and epilepsy

Twinning-assisted dynamic adjustment of grain boundary mobility

Grain boundary (GB) plasticity dominates the mechanical behaviours of nanocrystalline materials. Under mechanical loading, GB configuration and its local deformation geometry change dynamically with the deformation; the dynamic variation of GB deformability, however, remains largely elusive, especially regarding its relation with the frequently-observed GB-associated deformation twins in nanocrystalline materials. Attention here is focused on the GB dynamics in metallic nanocrystals, by means of well-designed in situ nanomechanical testing integrated with molecular dynamics simulations. GBs with low mobility are found to dynamically adjust their configurations and local deformation geometries via crystallographic twinning, which instantly changes the GB dynamics and enhances the GB mobility. This selfadjust twin-assisted GB dynamics is found common in a wide range of face-centred cubic nanocrystalline metals under different deformation conditions. These findings enrich our understanding of GB-mediated plasticity, especially the dynamic behaviour of GBs, and bear practical implication for developing high performance nanocrystalline materials through interface engineering

A tunable plasmonic refractive index sensor with nanoring-strip graphene arrays

In this paper, a tunable plasmonic refractive index sensor with nanoring-strip graphene arrays is numerically investigated by the finite difference time domain (FDTD) method. The simulation results exhibit that by changing the sensing medium refractive index nmed of the structure, the sensing range of the system is large. By changing the doping level ng, we noticed that the transmission characteristics can be adjusted flexibly. The resonance wavelength remains entirely the same and the transmission dip enhancement over a big range of incidence angles [0,45] for both TM and TE polarizations, which indicates that the resonance of the graphene nanoring-strip arrays is insensitive to angle polarization. The above results are undoubtedly a new way to realize various tunable plasmon devices, and may have a great application prospect in biosensing, detection and imaging

Improved SnO2 Electron Transport Layers Solution-Deposited at Near Room Temperature for Rigid or Flexible Perovskite Solar Cells with High Efficiencies

Electron transport layer (ETL) is a functional layer of great significance for boosting the power conversion efficiency (PCE) of perovskite solar cells (PSCs). To date, it is still a challenge to simultaneously reduce the surface defects and improve the crystallinity in ETLs during their low-temperature processing. Here, a novel strategy for the mediation of in situ regrowth of SnO2 nanocrystal ETLs is reported: introduction of controlled trace amounts of surface absorbed water on the fluorinated tin oxide (FTO) or indium-tin oxide (ITO) surfaces of the substrates using ultraviolet ozone (UVO) pretreatment. The optimum amount of adsorbed water plays a key role in balancing the hydrolysis-condensation reactions during the structural evolution of SnO2 thin films. This new approach results in a full-coverage SnO2 ETL with a desirable morphology and crystallinity for superior optical and electrical properties, as compared to the control SnO2 ETL without the UVO pretreatment. Finally, the rigid and flexible PSC devices based on the new SnO2 ETLs yield high PCEs of up to 20.5% and 17.5%, respectively

Mechanistic study of endothelium independent vasodilation effects of wogonin

34-40Scutellaria baicalensis Georgi, locally known as HuangQin, and commonly as Baikal or Chinese skullcap, is an important herb in Chinese traditional medicine. The flavonoids from this plant are main active substances responsible for its medicinal applications. Wogonin is one such active ingredient derived from this plant. Here, we investigated the mechanism of the vasodilation effect of wogonin on isolated rat thoracic aortas. For this study, endothelium intact and endothelium removed thoracic aortic rings were prepared from rats. Using a tension transducer, the tension of the rat thoracic aortic rings was recorded. Results showed that wogonin is able to relax the endothelium-intact aortic rings, but L-NAME, indomethacin (Indo), and methylene blue (MB) could not reduce the tension in these rings. Wogonin was also able to relax endotheliumremoved rings. However, treatment with tetraethylammonium (TEA), BaCl2, glibenclamide (Gly), 4-aminopyridine (4-AP), and verapamil (Ver) had no effect on vasodilation induced by wogonin. Using wogonin to pre-treat endothelium-removed aortic rings reduced the contraction induced by K+. Pre-treatment of endothelium-removed aortic rings with wogonin markedly reduced the contraction induced by 10-6 M PE in Ca2+-free solution. It could be concluded that L-type calcium channels and intracellular Ca2+ release is inhibited by wogonin