Structure, morphology, and mechanical properties of polysiloxane elastomer composites prepared by in situ polymerization of zinc dimethacrylate

Methyl vinyl silicone rubber/zinc dimethacrylate (VMQ/ZDMA) composites were prepared through in situ polymerization of ZDMA monomers during the peroxide curing. The polymerization conversion of ZDMA and morphology of the VMQ/ZDMA composites were studied. The results showed that most of the ZDMA monomers participated in the in situ polymerization during the cross-linking of the VMQ matrix and uniform nanophases were formed in the composites. The ‘dissolving-diffusion’ model was used to explain the micro-nano transformation of ZDMA. According to the model, a uniform nano-dispersed structure could be obtained through the in situ reaction even though the initial dispersion of ZDMA in the blends was poor. In addition, tensile tests of VMQ/ZDMA composites showed that ZDMA had a significant reinforcement on the mechanical properties of VMQ, and the best mechanical properties were obtained when the amounts of peroxide and ZDMA were 5 and 40 phr, respectively. The gross crosslink density and ionic crosslink density increased as the amount of ZDMA increased, but the covalent crosslink density decreased slightly. These results indicated that the ionic crosslink structure had a significant effect on the mechanical properties of VMQ/ZDMA composites

Effects of soil–structure interaction on the design of tuned mass damper to control the seismic response of wind turbine towers with gravity base

This paper studies the effect of soil–structural interaction (SSI) on gravity‐based wind turbine towers equipped with tuned mass dampers (TMDs) subjected to earthquake loading. A small‐scale shaking table test of wind turbine towers with TMD was conducted, and the results showed that using TMD designed considering SSI resulted in larger vibration suppression. A simplified analytical numerical model was developed for SSI analysis considering TMD. The effect of soil site class and the earthquake intensity on the response reduction efficiency of the TMD was also discussed using the simplified model. It is concluded that the TMD efficiency depends not only on the soil stiffness but also on the characteristics of the applied ground motions, both of which are affected by the site classes and earthquake intensity levels. Moreover, the peak acceleration ratio (PAR), the root mean square acceleration ratio (RAR), the peak displacement ratio (PDR), and the root mean square displacement ratio (RDR) of the top of the wind turbine tower were obtained with and without TMD for different earthquake intensities and sites. These parameters can be used as references for the rational selection of TMD parameters considering SSI

Impacts of inhomogeneous landscapes in oasis interior on the oasis self-maintenance mechanism by integrating numerical model with satellite data

The impacts of inhomogeneity of the oasis interior on the oasis self-maintenance mechanism are investigated by using the mesoscale model MM5 (the fifth-generation Pennsylvania State University National Center for Atmospheric Research (NCAR) mesoscale model) with satellite observations of land use types, vegetation fraction and surface-layer soil moisture from MODIS (Moderate Resolution Imaging Spectroradiometer) data. Four simulations were performed, among which the CTL (control simulation) and MOD (moderated simulation with parameters replaced by MODIS data) were used to validate the model results; EXP1 (experiment 1) and EXP2 (experiment 2) were designed to study the inhomogeneity of oasis interior. Results show that the changes of oasis heterogeneity influence the surface heat-flux partitioning, which leads to a larger "cold-wet" effect over the oasis. Vertical sections of humidity illustrate the existence of a moisture-inversion level, and the deeper moisture inversion of EXP1 and EXP2 further indicates that the relative homogeneity in the oasis interior helps produce stronger humidity inversion over the oasis, thus limiting evaporation. This is further verified by the analysis of the secondary circulation, which shows that the more homogeneous land surface conditions lead to stronger secondary circulation and less turbulent drafts over the oasis interior, playing a positive role in the oasis self-maintenance and development

Measurement Report: Investigation on the sources and formation processes of dicarboxylic acids and related species in urban aerosols before and during the COVID-19 lockdown in Jinan, East China

Dicarboxylic acid (diacid) homologs are essential indicators of secondary organic aerosols (SOA) that exert a considerable influence on climate changes and atmospheric chemistry. However, their sources and formation processes are poorly understood, leading to uncertainty in predicting the climate effect of SOA. A substantial drop in anthropogenic emissions during the COVID-19 lockdown (LCD) provides a “controlled experiment” to explore the effects of LCD measures and meteorological conditions on SOA. Here we investigated the difference in molecular distributions and stable carbon isotopic compositions (δ13C) of diacid homologs in PM2.5 before and during the LCD. We found that the concentration and contribution of diacid homologs during the LCD were higher than before the LCD, indicating that the enhanced secondary oxidation could offset the reduction in anthropogenic emissions during the LCD. A higher oxalic acid (C2) / diacid ratio and more positive δ13C values of major diacids during the LCD suggested more aged organic aerosols. The enhanced C2 and related species during the LCD were mainly derived from the promoted gaseous photochemical oxidation by the higher oxidants and stronger solar radiation. However, C2 and related species before the LCD were dominantly derived from the aqueous oxidation of α-dicarbonyls depending on relative humidity and liquid water content. The increased δ13C values of C2 and other major diacids along with the high ratios of C2 / glyoxal, C2 / methylglyoxal, and C2 / diacid confirmed an isotopic fractionation effect during the oxidation process of precursors. Our results indicate that atmospheric pollution treatment depends on a balanced strategy and a coordinated effort to control multiple pollutants.</p

Linkage analysis of economic consumption, pollutant emissions and concentrations based on a city-level multi-regional input–output (MRIO) model and atmospheric transport

China is experiencing serious atmospheric pollution, which also exhibits significant spatial heterogeneity. The Chinese government has implemented targeted pollution control measures at the city level, emphasizing coordination among cities to prevent and control air pollution in key regions such as Beijing–Tianjin–Hebei (BTH) urban agglomeration. This study combined an inter-city multi-regional input–output (MRIO) model with an air quality dispersion model consisting of a weather research and forecasting (WRF) model and the CALPUFF model (WRF/CALPUFF) to study the inter-city economic consumption, pollutant emission and concentration among 13 cities in BTH urban agglomeration. NOx is chosen as an example. The combined effects of economic linkage and atmospheric transport show that NOx concentrations in cities in the BTH urban agglomeration are attributable to three consumption sources: a local contribution from the target city's own local economic consumption (average, 25%), and non-local consumption contributions, including other cities in the BTH urban agglomeration (average, 36%) and regions outside of BTH (average, 39%). Compared with the contributions to NOx concentrations calculated using only the MRIO model or atmospheric transport stimulation model, the results of this paper quantify that the consumption outside of a city could provide a greater impact on the city's air quality due to the combined effects of economic linkage and atmospheric transport. To avoid negative impacts of emission reduction targets on economic consumption, governmental regional pollution control policies should consider the combined effects of economic linkage and atmospheric transport

A regulatory network for human adenocarcinoma

Human adenocarcinoma (AC) is the most frequently diagnosed human lung cancer and its absolute incidence is increasing dramatically. Our study aimed to interpret the mechanisms of human adenocarcinoma through the  regulation network based on differentially expressed genes (DEGs). We used the GSE2514 microarray data to identify human adenocarcinoma differentially expressed genes. Based on these genes and collected regulation datasets, 129 relationships between transcription factor and their target genes were established in AC. Finally, we find some new candidates and relationships, such as IL6 and NFKB1 owning a close connection with AC. Based on a relatively small number of patients, the results will need to be repeated and confirmed in future studies.Key words: Adenocarcinoma, transcription factors, transcriptome

Fabrication of uniform Ge-nanocrystals embedded in amorphous SiO[sub 2] films using Ge-ion implantation and neutron irradiation methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98678/1/ApplPhysLett_98_073103.pd