Iterative Virtual Force Localization Based on Anchor Selection for Three-Dimensional Wireless Sensor Networks

Network localization is an emerging paradigm that enables high-accuracy location awareness in global positioning system (GPS)-challenged environments. The existing localization methods suffer from low accuracy, inflexible node distribution, and high hardware cost, especially in three-dimensional (3D) environment. To develop an efficient 3D localization method, this paper proposes the iterative virtual force (IVF) localization based on anchor selection. To eliminate the distance estimation error of range-free measurement, the K-means clustering (KMC) was introduced to exclude anchors with distance outliers, forming a set of selected anchors, which is enclosed as a virtual space. Based on the centroid of the virtual space, a drifting coefficient was defined, and the balance point of virtual force was deduced. The centroid was drifted to the balance point, and used to replace the anchor with the farthest distance to agent, producing a new set of selected anchors. In this way, the IVF method iteratively localizes the agent. In addition, the authors configured the threshold of change rate, and proved the condition of faster convergence. Simulation results show that the IVF method excels in localization accuracy, hardware cost, and computing complexity. Our research widens the application scope and improves the robustness of IVF localization in complex 3D WSNs

Multiobjective Optimization of the Performance and Emissions of a Large Low-Speed Dual-Fuel Marine Engine Based on MNLR-MOPSO

With increasingly strict emission regulations and growing environmental concerns, it is urgent to improve engine performance and reduce emissions. In this paper, multivariate nonlinear regression (MNLR) combined with multiobjective particle swarm optimization (MOPSO) was implemented to optimize the performance and emissions of a large low-speed two-stroke dual-fuel marine engine. First, a simulation model of a dual-fuel engine was established using AVL-BOOST software. Next, a single-factor scanning value method was applied to control a range of variables, including intake pressure, intake temperature, and natural gas mass fraction. Then, a nonlinear regression model was established using the statistical multivariate nonlinear regression equation. Finally, the multiobjective optimization algorithm implementing MOPSO was used to solve the trade-off between performance and emissions. It was found that when the intake pressure was 3.607 bar, the intake temperature was 297.15 K and the natural gas mass fraction was 0.962. The engine power increased by 0.34%, the brake specific fuel consumption (BSFC) reduced by 0.21%, and the NOx emissions reduced by 39.56%. The results show that the combination of multiple nonlinear regression and intelligent optimization algorithm is an effective method to optimize engine parameter settings

Cyclodextrin/chitosan nanoparticles for oral ovalbumin delivery: Preparation, characterization and intestinal mucosal immunity in mice

A novel oral protein delivery system with enhanced intestinal penetration and improved antigen stability based on chitosan (CS) nanoparticles and antigen-cyclodextrin (CD) inclusion complex was prepared by a precipitation/coacervation method. Ovalbumin (OVA) as a model antigen was firstly encapsulated by cyclodextrin, either β-cyclodextrin (β-CD) or carboxymethyl-hydroxypropyl-β-cyclodextrin (CM-HP-β-CD) and formed OVA-CD inclusion complexes, which were then loaded to chitosan nanoparticles to form OVA loaded β-CD/CS or CM-HP-β-CD/CS nanoparticles with uniform particle size (836.3 and 779.2 nm, respectively) and improved OVA loading efficiency (27.6% and 20.4%, respectively). In vitro drug release studies mimicking oral delivery condition of OVA loaded CD/CS nanoparticles showed low initial releases at pH 1.2 for 2 h less than 3.0% and a delayed release which was below to 30% at pH 6.8 for further 72 h. More importantly, after oral administration of OVA loaded β-CD/CS nanoparticles to Balb/c mice, OVA-specific sIgA levels in jejunum of OVA loaded β-CD/CS nanoparticles were 3.6-fold and 1.9-fold higher than that of OVA solution and OVA loaded chitosan nanoparticles, respectively. In vivo evaluation results showed that OVA loaded CD/CS nanoparticles could enhance its efficacy for inducing intestinal mucosal immune response. In conclusion, our data suggested that CD/CS nanoparticles could serve as a promising antigen-delivery system for oral vaccination. Keywords: β-cyclodextrin, Chitosan nanoparticles, Ovalbumin, Oral protein delivery, Intestinal mucosal immunit

Plastic mulching, and occurrence, incorporation, degradation, and impacts of polyethylene microplastics in agroecosystems

Polyethylene microplastics have been detected in farmland soil, irrigation water, and soil organisms in agroecosystems, while plastic mulching is suggested as a crucial source of microplastic pollution in the agroecosystem. Plastic mulch can be broken down from plastic mulch debris to microplastics through environmental aging and degradation process in farmlands, and the colonization of polyethylene-degrading microorganisms on polyethylene microplastics can eventually enzymatically depolymerize the polyethylene molecular chains with CO2 release through the tricarboxylic acid cycle. The selective colonization of microplastics by soil microorganisms can cause changes in soil microbial community composition, and it can consequently elicit changes in enzyme activities and nutrient element content in the soil. The biological uptake of polyethylene microplastics and the associated disturbance of energy investment are the main mechanisms impacting soil-dwelling animal development and behavior. As polyethylene microplastics are highly hydrophobic, their presence among soil particles can contribute to soil water repellency and influence soil water availability. Polyethylene microplastics have been shown to cause impacts on crop plant growth, as manifested by the effects of polyethylene microplastics on soil properties and soil biota in the agroecosystems. This review reveals the degradation process, biological impacts, and associated mechanisms of polyethylene microplastics in agroecosystems and could be a critical reference for their risk assessment and management

WO₃-Nanocrystal-Modified Electrodes for Ultra-Sensitive and Selective Detection of Cadmium (Cd²⁺) Ions

The detection of heavy metal ions is becoming increasingly important for environmental monitoring and personal safety protection. Owing to their large surface area and suitable conductivity, metal oxide semiconductor nanocrystals have been utilized in chemically modified electrodes for the rapid and low-cost detection of heavy metal ions. However, their sensitivity and selectivity for cadmium ion (Cd2+) detection still remains a challenge. Here, a method of ultra-sensitive and selective Cd2+ detection based on WO3-nanocrystal-modified electrodes is proposed and demonstrated. Colloidal WO3 nanocrystals were synthesized via a solvothermal route and then deposited onto a carbon electrode using a spin-coating method, forming the modification layer at room temperature. The WO3-nanocrystal-modified electrodes exhibit a remarkable signal transduction capability that converts Cd2+ adsorption into current output signals. The peak current was linear to the logarithm of the Cd2+ concentration from 1 nM to 10,000 nM when measured using the anodic stripping voltammetry method. The selectivity mechanism was studied and attributed to the high adsorption energy of cadmium on WO3 compared to other heavy metal ions. Employment of WO3 for a high-performance Cd2+-selective electrode opens many opportunities in portable ion-detection applications

Cbln1 and Cbln4 Are Structurally Similar but Differ in GluD2 Binding Interactions

Unlike cerebellin 1 (Cbln1), which bridges neurexin (Nrxn) receptors and δ-type glutamate receptors in a trans-synaptic triad, Cbln4 was reported to have no or weak binding for the receptors despite sharing ∼70% sequence identity with Cbln1. Here, we report crystal structures of the homotrimers of the C1q domain of Cbln1 and Cbln4 at 2.2 and 2.3 Å resolution, respectively. Comparison of the structures suggests that the difference between Cbln1 and Cbln4 in GluD2 binding might be because of their sequence and structural divergence in loop CD. Surprisingly, we show that Cbln4 binds to Nrxn1β and forms a stable complex with the laminin, nectin, sex-hormone binding globulin (LNS) domain of Nrxn1β. Furthermore, the negative-stain electron microscopy reconstruction of hexameric full-length Cbln1 at 13 Å resolution and that of the Cbln4/Nrxn1β complex at 19 Å resolution suggest that Nrxn1β binds to the N-terminal region of Cbln4, probably through strand β10 of the S4 insert