On Propagation Loss for Reconfigurable Surface Wave Communications

Surface wave communication (SWC) is an emerging technology garnering significant interest for its diverse potential applications in communications. However, accurately computing electromagnetic field strength, which is related to the path loss, in reconfigurable surface structures, particularly for long-distance transmission, presents an ongoing challenge. To address this, we introduce a novel analytical model employing surface wave ray tracing. Unlike conventional simulations, our analytical approach enables precise computation of the electromagnetic field strength attenuation in both short and long-distance transmissions, providing invaluable insights for practical SWC implementations. Our proposed model takes into account key system parameters such as surface material, thickness, cavity porosity, and other variables influencing propagation performance. This facilitates analysis of optimal reconfigurable structures. Simulation results validate the model’s accuracy in short-distance transmission, thereby endorsing its effectiveness in studying surface wave path loss over longer distances. Furthermore, our study demonstrates the SWC superiority over traditional coaxial cable and space-wave communication in mitigating path loss. Additionally, we explore the impacts of various factors such as different dielectric layers, wall materials, leakage, and pathway width on SWC performance, providing deeper insights into designing optimal reconfigurable structures for SWC applications

Path Loss and Surface Impedance Models for Surface Wave-Assisted Wireless Communication System

Surface wave-assisted wireless communication systems have recently emerged as a promising complementary solution for creating a smart radio environment, particularly in the context of beyond-fifth generation (5G) and sixth generation (6G) networks. Unlike traditional approaches that rely solely on space waves or use passive elements on a large surface to reflect space waves, the incorporation of surface waves can effectively address challenges such as blockage and severe path loss, which are prevalent at extremely high frequencies, including millimeter wave (mmWave) and terahertz (THz) bands. Recent advances in metasurface properties have enabled the propagation of electromagnetic waves on a surface without re-radiation. Motivated by these developments, in this paper, we develop a path loss model and two surface impedance models for surface wave-assisted wireless communication systems. We demonstrate that the signal-to-noise ratio (SNR) of this system can be significantly higher than that of traditional wireless communication systems because the path loss for a surface wave is proportional to the propagation distance, whereas the path loss for a space wave is proportional to the square of the propagation distance. Furthermore, we explore how the metasurface should be designed in terms of its materials and structures, considering that the incident space wave must be aligned with Brewster’s angle to excite a surface wave

Induced Wood-Inorganic Composites in Standing Trees via Slow-Release Drip

It is a novel idea to fabricate wood-inorganic composites by utilizing the transpiration of bionic trees to realize the self-assembly of inorganic precursors in wood formation. We selected a 10-year-old poplar and diffused the solvent or sol containing SiO2 precursor into the xylem via the slow-release drip method. In combination with the moisture in xylem, reactions such as hydrolysis, polycondensation and self-assembly were induced in order to form wood inorganic composites. It was found, through microscopic observation, that such inorganic substances were yellowish brown and widely existed in vessels, wood fibers and ray cells. For the new grown wood, the fiber–tissue ratio and cell wall thickness underwent an increase, while the vessel diameter and tissue ratio experienced a decline. Moreover, such change was related to the concentration of precursors. EDS analysis proved that the elemental composition of sediments in wood cells was C, O, Si, K and Ca. XPS confirmed that the newly formed wood contained silicon oxide, illustrating that the standing tree slow-release drip technology could induce wood to fabricate inorganic composites

Identification of Time-Varying Parameters of Distributed Hydrological Model in Wei River Basin on Loess Plateau in the Changing Environment

In the watershed hydrological model, the parameters represent the characteristics of the watershed. Usually, the parameters are assumed to be constant in the stable environment. However, in the changing environment, the parameters may change and the constant parameters would not represent the change of the characteristics of the runoff generation and routing in the watershed. The identification of the time-varying characteristics of the watershed hydrological model parameters will help to improve the performance of the simulation and prediction of hydrological models in changing environments. Based on the measured data at the ground stations in the Wei River Basin on the Loess Plateau in China, the temporal and spatial evolution of the ecohydrological and meteorological factors was analyzed, and the SWAT model was used to identify the relationship between the model parameters and the factors, such as precipitation, potential evapotranspiration, NDVI and the other environmental characterization factors of the river basin. The results showed that the annual precipitation in the basin showed a decreasing trend, and the annual potential evapotranspiration, the annual average temperature, the annual runoff and the annual average NDVI all showed an increasing trend. The model parameters fluctuated with time during the study period. The change of the soil evaporation compensation coefficient (ESCO) was similar with the annual potential evapotranspiration, and the model parameters all showed a certain correlation with the potential evaporation of the basin, which indicates that the changes of the hydrological model parameters in the upper reach of the Wei River are closely related to the changes of the basin potential evapotranspiration. Potential evapotranspiration is a characterization factor for dynamic changes of the hydrological model parameters in the upper reach of the Wei River

The Isoquinoline Alkaloid Dauricine Targets Multiple Molecular Pathways to Ameliorate Alzheimer-Like Pathological Changes In Vitro

Alzheimer’s disease (AD), the most common neurodegenerative disease, has no effective treatment. Dauricine (DAU), a benzyl tetrahydroisoquinoline alkaloid isolated from the root of Menispermum dauricum DC, reportedly has neuroprotective effects in cerebral ischemia. Here, we investigated the effects of DAU on N2a cells stably transfected with Swedish mutant amyloid precursor protein (N2a/APP), an AD-like cell model. ELISA and Western blot analysis revealed that DAU inhibited APP processing and reduced Aβ accumulation. In addition, DAU ameliorated tau hyperphosphorylation via PP2A, p35/25, and CDK5 pathways in N2a/APP cells. The amelioration of tau hyperphosphorylation by DAU was also validated in HEK293/Tau cells, another cell line with tau hyperphosphorylation. Proteomic analysis revealed 85 differentially expressed proteins in the lysates between the wild-type N2a cells (N2a/WT) and the N2a/APP cells in the presence or absence of DAU; these were classified into 6 main categories according to their functions: endoplasmic reticulum (ER) stress-associated proteins, oxidative stress-associated proteins, cytoskeleton proteins, molecular chaperones, mitochondrial respiration and metabolism-related proteins, and signaling proteins. Taken together, we demonstrated that DAU treatment reduces AD-like pathology, thereby suggesting that DAU has potential therapeutic utility in AD

The relationship of endothelial function and arterial stiffness with subclinical target organ damage in essential hypertension

Abstract This study aimed to explore whether brachial‐ankle pulse wave velocity (baPWV) and brachial artery flow‐mediated dilation (FMD) or the interaction of both parameters are associated with subclinical target organ damage (STOD) indices in patients with essential hypertension. A total of 4618 patients registered from January 2015 to October 2020 were included. baPWV and FMD were measured to evaluate arterial stiffness and endothelial dysfunction. Whereas left ventricular hypertrophy (LVH), urine albumin‐creatinine ratio (UACR), and carotid intima‐media thickness (CIMT) were obtained as STOD indicators. On multivariable logistic regression analysis with potential confounders, higher quartiles of baPWV and FMD were significantly associated with an increased risk of STOD. In patients <65 years of age, the odds ratio (OR) of LVH, UACR, and CIMT ≥.9 mm for the fourth versus the first quartile of baPWV were 1.765 (1.390–2.240), 2.832 (2.014–3.813), and 3.075 (2.315–4.084), respectively. In interaction analysis, an increase in baPWV shows a progressively higher risk of STOD across the quartiles of FMD. Also, the estimated absolute risks of LVH, UACR, and CIMT ≥.9 mm for the first to fourth quartile of baPWV increased from 1.88 to 2.75, 2.35 to 4.44, and 3.10 to 6.10, respectively, in patients grouped by FMD quartiles. The addition of baPWV to FMD slightly improved risk prediction for STOD. BaPWV and FMD were independently associated with an increased risk of STOD in patients with essential hypertension especially among patients <65 years of age. Patients with elevated baPWV and decreased FMD parameters are at increased risk of STOD