PN Codes Estimation of Binary Phase Shift Keying Signal Based on Sparse Recovery for Radar Jammer.

Parameter estimation is extremely important for a radar jammer. With binary phase shift keying (BPSK) signals widely applied in radar systems, estimating the parameters of BPSK signals has attracted increasing attention. However, the BPSK signal is difficult to be processed by traditional time frequency analysis methods due to its phase jumping and abrupt discontinuity features which makes it difficult to extract PN (PN) codes of the BPSK signal. To solve this problem, a two-step PN codes estimation method based on sparse recovery is introduced in this paper. The proposed method first pretreats the BPSK signal by estimating its center frequency and converting it to zero intermediate frequency (ZIF). The pretreatment transforms phase jumps of the BPSK signal into the level jumps of the ZIF signal. By nonconvex sparsity promoting regularization, the level jumps of the ZIF signal are extracted through an iterative algorithm. Its effectiveness is verified by numeric simulations and semiphysical tests. The corresponding results demonstrate that the proposed method is able to estimate PN codes from the BPSK signal in serious electromagnetic environments.

Necroptosis signaling and NLRP3 inflammasome cross-talking in epithelium facilitate Pseudomonas aeruginosa mediated lung injury.

Pseudomonas aeruginosa induced acute lung injury is such a serious risk to public health, but the pathological regulation remains unclear. Here, we reported that PA mediated epithelial necroptosis plays an important role in pathological process. Pharmacological and genomic ablation of necroptosis signaling ameliorate PA mediated ALI and pulmonary inflammation. Our results further proved NLRP3 inflammasome to involve in the process. Mechanism investigation revealed the cross-talking between inflammasome activation and necroptosis that MLKL-dependent necroptosis signaling promotes the change of mitochondrial membrane potential for the release of reactive oxygen species (ROS), which is the important trigger for functional inflammasome activation. Furthermore, antioxidants such as Mito-TEMPO was confirmed to significantly restrain inflammasome activation in epithelium, resulting in a reduction in PA induced pulmonary inflammation. Taken together, our findings revealed that necroptosis-triggered NLRP3 inflammasome in epithelium plays a crucial role in PA mediated injury, which could be a potential therapeutic target for pulmonary inflammation.

DDR1 activation in macrophage promotes IPF by regulating NLRP3 inflammasome and macrophage reaction.

BACKGROUND: Discoidin Domain Receptor1 (DDR1) is a member of receptor tyrosine kinases (RTKs) which have been reported to be associated with idiopathic pulmonary fibrosis (IPF), but the mechanism remains unclear. METHODS: Bleomycin-induced IPF mice model was performed in this study, and two DDR1 inhibitors were administered in vivo, to investigate the role of DDR1 in IPF. Lentivirus mediated DDR1-/- stable Raw264.7 macrophage cell line or DDR1 inhibitors treatment in vitro, to study the effect of DDR1 on inflammasome activation and macrophage responses. All of the mechanisms were further tested in the lung sections of IPF patients. RESULT: Here, we reported that: (i) Both specific inhibitors of DDR1 dramatically alleviated the symptoms of bleomycin-induced IPF models. (ii) Immunofluorescence staining showed that DDR1 signaling is activated in macrophages. In vivo molecular biological analysis proved that DDR1 activation exacerbates IPF inflammation through inflammasome signaling, macrophage activation, and M1/M2 polarization. (iii) Extracellular matrix (ECM) such as Collagen 1 activates DDR1 in macrophage cell line Raw264.7 in vitro, to mediate inflammasome activation and macrophage responses. (iv) DDR1 activation in macrophage was confirmed in IPF patients' samples, which could be one of the mechanisms for the pathogenesis of IPF. DISCUSSION: In this study, we firstly reported DDR1 activation in macrophages to play a role in IPF via inflammasome activation and macrophage responses. In addition, DDR1 inhibitors DDR1-IN-1 and DDR1-IN-2 exerted significant anti-inflammatory and anti-fibrotic effects in IPF, all of which provide a potentially effective therapeutic medication for clinical IPF treatment.

Synthesis, Simulation, and Self-Assembly of a Model Amphiphile To Push the Limits of Block Polymer Nanopatterning.

Efforts to create block-polymer-based templates with ultrasmall domain sizes has stimulated integrated experimental and theoretical work in an effort to design and prepare self-assembled systems that can achieve unprecedented domain sizes. We recently reported the utilization of molecular dynamics simulations with transferable force fields to identify amphiphilic oligomers capable of self-assembling into ordered layered and cylindrical morphologies with sub-3 nm domain sizes. Motivated by these predictions, we prepared a sugar-based amphiphile with a hydrocarbon tail that shows thermotropic self-assembly to give a lamellar mesophase with a 3.5 nm pitch and sub-2 nm nanodomains above the melting temperature and below the liquid-crystalline clearing temperature. Complementary atomistic simulations of the molecular assemblies gave morphologies and spacings that were in near-perfect agreement with the experimental results. The effective combination of molecular design, simulation, synthesis, and structural characterization demonstrates the power of this integrated approach for next-generation templating technologies.

Renewable lubricants with tailored molecular architecture.

We present a strategy to synthesize three types of renewable lubricant base oils with up to 90% yield using 2-alkylfurans, derived from nonfood biomass, and aldehydes, produced from natural oils or biomass through three chemistries: hydroxyalkylation/alkylation (HAA), HAA followed by hydrogenation, and HAA followed by hydrodeoxygenation. These molecules consist of (i) furan rings, (ii) saturated furan rings, and (iii) deoxygenated branched alkanes. The structures of these molecules can be tailored in terms of carbon number, branching length, distance between branches, and functional groups. The site-specific, energy-efficient C-C coupling chemistry in oxygenated biomass compounds, unmatched in current refineries, provides tailored structure and tunable properties. Molecular simulation demonstrates the ability to predict properties in agreement with experiments, proving the potential for molecular design.

Using molecular simulations to probe pore structures and polymer partitioning in size exclusion chromatography.

Molecular simulations have been extensively utilized to understand and predict the polymer partitioning in size-exclusion chromatography (SEC). However, idealized pore models (e.g., cylindrical, spherical, and slit pores) were often used to represent the porous media in an SEC column, which leads to significant deviations in describing the geometry and the size of the pores. In this work, several complex pore models were derived from body-centered cubic, random, and gel packing of monodisperse spherical sol particles using simulation methodology. The mechanical stabilities of these structures were determined based on particle coordination numbers. Pore size distributions of these porous structures were compared to a commercially available, wide-pore superficially porous particle. Then, Gibbs ensemble Monte Carlo simulations were performed to compute the pore-to-bulk partitioning coefficient KSEC of a polymer chain with complex pore models. The effects of particle size, packing structure, and porosity on KSEC were explored. In addition, structural analysis provides insight into the conformation of polymers in the pores and its effect on the partitioning behavior. This study promotes the understanding of pore structures in SEC columns and enables more accurate predictions of KSEC with less ambiguity in pore geometry.

Computational Design of High-χ Block Oligomers for Accessing 1 nm Domains.

Molecular dynamics simulations are used to design a series of high-χ block oligomers (HCBOs) that can self-assemble into a variety of mesophases with domain sizes as small as 1 nm. The exploration of these oligomers with various chain lengths, volume fractions, and chain architectures at multiple temperatures reveals the presence of ordered lamellae, perforated lamellae, and hexagonally packed cylinders. The achieved periods are as small as 3.0 and 2.1 nm for lamellae and cylinders, respectively, which correspond to polar domains of approximately 1 nm. Interestingly, the detailed phase behavior of these oligomers is distinct from that of either solvent-free surfactants or block polymers. The simulations reveal that the behavior of these HCBOs is a product of an interplay between both "surfactant factors" (headgroup interactions, chain flexibility, and interfacial curvature) and "block polymer factors" (χ, chain length N, and volume fraction f). This insight promotes the understanding of molecular features pivotal for mesophase formation at the sub-5 nm length scale, which facilitates the design of HCBOs tailored toward particular desired morphologies.

Using the k-d Tree Data Structure to Accelerate Monte Carlo Simulations.

The k-d tree data structure is implemented in a Monte Carlo (MC) molecular simulation program to accelerate the range search for particles or interaction sites within the cutoff distance when Lennard-Jones and Coulomb interactions are computed. MC simulations are performed for different molecules in various ensembles to assess the efficiency enhancements due to the k-d tree data structure. It is found that the use of k-d trees accelerates significantly simulations for Lennard-Jones particles in the NVT and NVT-Gibbs ensembles and for n-butane and 2,4,6,8,10,12,14,16,18,20,22-undecamethylpentacosane represented by the TraPPE-UA force field in the NpT ensemble. Simulations for TraPPE-UA ethanol in the NpT ensemble and for the rigid TIP4P water model in the Gibbs ensemble gain slightly in efficiency with the k-d tree, whereas simulations for TIP4P water in the NpT ensemble do not benefit from the use of the k-d tree. The speed-up can be attributed to the reduction in the number of distance calculations in the range search from scaling as [Formula: see text] to [Formula: see text]. In addition, these tests suggest that the efficiency gain from the use of the k-d tree data structure depends on the flexibility of the molecular model (requiring configurational-bias MC moves to sample changes in conformation), on the ensemble (with open ensembles requiring special MC moves to aid particle transfers), and on the number of interaction sites per molecule (with compact multisite models not seeing an efficiency gain). Overall, the use of the k-d tree data structure can substantially enhance MC simulation efficiency for a variety of systems, and it will enable simulations for larger system sizes in the future.

Electrokinetic desalination using honeycomb carbon nanotubes (HC-CNTs): a conceptual study by molecular simulation.

A new concept of electrokinetic desalination using a CNT honeycomb is presented through molecular dynamics simulation. The preferential translocation of ions towards the outlets near two electrodes was realized by applying an electric field perpendicular to bulk fluid flow in a CNT network, which, in the meantime, generated deionized water flux discharged from the central outlets. The effects of the major factors such as electric field strength, numbers of separation units, diameter of CNT, and ion concentration on the desalination were examined. It was shown that over 95% salt rejection and around 50% fresh water recovery were achieved by the presented module by applying an electric field of 0.8 V nm(-1). CNT diameter, which is critical to ion rejection without the electric field, had a marginal effect on the desalination of this new module when a strong electric field was applied. The desalination was also not sensitive to ion concentration, indicating its excellent workability for a wide range of water salinity, e.g. from brackish water to seawater. A potential of mean force profile revealed a free energy barrier as large as 2.0-6.0 kcal mol(-1) for ions to move opposite to the implemented electrical force. The simulation confirmed the high potential of the CNT honeycomb in water desalination.

Controlled display of enzyme activity with a stretchable hydrogel.

An enzyme-incorporated hydrogel made of alginate and polyacrylamide shows a linearly increased activity with the enlargement of surface area upon stretching.