Due to their small size, differential microphone arrays (DMAs) are very attractive. Moreover, they have been effective in combating noise and reverberation. Recently, a new class of DMAs of different ...orders have been developed with the MacLaurin’s series and the frequency-independent patterns. However, the MacLaurin’s series does not approximate well the exponential function, which appears in the general definition of the beampattern, when the intersensor spacing is not small enough. To circumvent this problem, we propose in this paper to approximate the exponential function with the Jacobi–Anger expansion. Based on this approximation and the frequency-independent Chebyshev patterns, we derive first-, second-, and third-order DMAs. Furthermore, in order to improve the robustness of DMAs against white noise amplification, we propose to use more microphones combined with minimum-norm filters. It is also shown that the Jacobi–Anger expansion is optimal from a mean-squared error perspective. Simulations are carried out to evaluate the performance of the proposed DMAs.
A copper(II)‐catalyzed oxidative methylene‐bridged dimerization of two analogous imidazo1,2‐apyridines has been achieved using N,N‐dimethylacetamide (DMA) as solvent cum methylene source. This ...reaction works with a variety of substituted imidazo1,2‐apyridines giving their products in moderate to good yields. Isotopic labelling experiments revealed that the methylene group in the product originates from the N,N‐dimethyl moiety of DMA.
For the first time, phytosiderophore (PS) release of wheat (Triticum aestivum cv Tamaro) grown on a calcareous soil was repeatedly and nondestructively sampled using rhizoboxes combined with a ...recently developed root exudate collecting tool. As in nutrient solution culture, we observed a distinct diurnal release rhythm; however, the measured PS efflux was c. 50 times lower than PS exudation from the same cultivar grown in zero iron (Fe)‐hydroponic culture. Phytosiderophore rhizosphere soil solution concentrations and PS release of the Tamaro cultivar were soil‐dependent, suggesting complex interactions of soil characteristics (salinity, trace metal availability) and the physiological status of the plant and the related regulation (amount and timing) of PS release. Our results demonstrate that carbon and energy investment into Fe acquisition under natural growth conditions is significantly smaller than previously derived from zero Fe‐hydroponic studies. Based on experimental data, we calculated that during the investigated period (21–47 d after germination), PS release initially exceeded Fe plant uptake 10‐fold, but significantly declined after c. 5 wk after germination. Phytosiderophore exudation observed under natural growth conditions is a prerequisite for a more accurate and realistic assessment of Fe mobilization processes in the rhizosphere using both experimental and modeling approaches.
La discusión sobre la regulación de plataformas se ha centrado, tanto en la academia, como en organismos internacionales y agencias de la competencia, en las herramientas del modelo neoclásico de ...regulación: cuotas de mercado y análisis de bienestar, entre otras. Más recientemente el big data y los algoritmos han pasado a ser centrales en estos debates. El objetivo de este artículo es analizar, desde una perspectiva crítica, la evolución de esta discusión, su impacto en las diferentes propuestas legislativas, y el largo período que llevó a la Unión Europea a adoptar, en 2022, la regulación de estas corporaciones. Adicionalmente, se sugieren nuevos instrumentos de políticas públicas que puedan superar estas nuevas normativas.
•The initial moisture content in CFRP tendons affects significantly the Tg values.•CFRP specimens without initial moisture content should be used for quality control.•Plasticisation effects in CFRP ...tendons due to exposure in water are reversible.•The fire performance of CFRP tendons can be affected by the initial moisture content.•The magnitude of static flexural strain and specimen geometry do not affect the Tg.
The high temperature and long-term performance of uni-directional pultruded carbon fibre reinforced polymer (CFRP) tendons in prestressed concrete relies on the integrity of the epoxy matrix and the degree of crosslinking. The dynamic glass transition temperature (Tg) obtained using Dynamic Mechanical Analysis (DMA) can be a useful indicator of the degree of cross-linking. However, variations in the epoxy plasticisation due to different initial hygrothermal equilibrium conditions in CFRP tendons can influence the measured Tg leading to inconsistent results. The dependency of Tg on the initial CFRP moisture content, and also DMA test parameters including the thermocouple position, the magnitude of static flexural strain, the static to dynamic strain ratio and the specimen geometry were investigated. Whereas the selected DMA test parameters had only a small influence on the Tg values, the initial moisture content of the CFRP tendon had a significant effect. A decrease in Tg of up to 38 °C was observed with an increase in average moisture content of up to 2.46%. Knowledge of the initial moisture content and the establishment of a comparative baseline are necessary to more accurately infer the crosslinking density and degree of cure of a resin from dynamic Tg results.
Normalizing the tumor‐induced immune deficiency in the immunosuppressive tumor microenvironment (TME) through increasing the efficient infiltration and activation of antitumoral immunity in TME is ...the core of promising immunotherapy. Herein, a Cyclo(Arg‐Gly‐Asp‐d‐Phe‐Lys) (RGD) peptides‐modified combinatorial immunotherapy system based on the self‐assembly of the nanoparticles named RGD‐DMA composed of RGD‐PEG‐PLA, methoxy poly(ethylene glycol)‐poly(lactide) (MPEG‐PLA) and 1,2‐Dioleoyl‐3‐trimethylammonium‐propane (DOTAP) is used to codeliver the immunostimulatory chemokine CCL19‐encoding plasmid DNA (CCL19 pDNA) and immune checkpoint ligand PD‐L1 inhibitor (BMS‐1). The RGD‐DMA/pCCL19‐BMS‐1 system not only exhibited significant inhibition of tumor progression but also induced locally high concentrations of immunostimulatory cytokines at tumor sites without causing an obviously systemic inflammatory response. The immunosuppressive TME is efficaciously reshaped by the coadministration of RGD‐DMA/pCCL19 and BMS‐1, as indicated by the activated T lymphocytes, increased intratumoral‐infiltration of mature dendritic cells (DCs), and the repolarization of macrophages from pro‐tumoral M2‐phenotype toward tumoricidal M1‐phenotype. The upregulated PD‐L1 expression at tumor sites caused by the increased IFN‐γ levels after immunostimulatory gene therapy further demonstrated the synergistic effects of BMS‐1 in counteracting the inhibitory role of PD‐L1 expression in antitumor immunity. Therefore, the combination of immunostimulating therapy and immune checkpoint inhibitor that synergistically target multiple immune regulatory pathways demonstrates significant potential as a novel immunotherapy approach.
The combined immunotherapy by RGD‐DMA nanoparticles delivering pDNA encoding the immunostimulating chemokine CCL19 with immune checkpoint small molecular inhibitor BMS‐1 synergistically targets multiple immune regulatory pathways, as indicated by inducing the activation of lymphocytes, repolarizing tumor‐associated macrophages toward a tumoricidal M1 phenotype as well as promoting the maturation of tumor‐infiltrating dendritic cells in the tumor microenvironment (TME). The codelivery of CCL19 plasmid DNA and BMS‐1 by RGD‐DMA significantly reshapes the immunosuppressive TME and leads to a strong antitumor effect.
This study aims to improve the thermal and mechanical properties of epoxy-based materials. For this purpose, the structure of epoxy resins was changed by chemical modification and epoxy resin ...containing urethane was synthesized. The synthesized resin was blended with commercial epoxy resin at the ratios of 25%, 50%, 75% by weight and hardened by curing. The thermal and mechanical properties of urethane-containing epoxy materials prepared in different proportions were compared with those produced from commercial epoxy resin. The structural characterization of the prepared materials was investigated by Fourier Transform Infrared Spectroscopy (FTIR) analysis, their thermal behavior was investigated by Thermogravimetric Analysis (TGA), and their mechanical properties were investigated by Dynamic Mechanical Analysis (DMA). TGA and DMA analyses of the materials showed that the presence of urethane in the structure of epoxy resins significantly changed the mechanical and thermal properties. It was observed that the storage and loss modulus values of urethane-containing resins increased approximately 2.5 times compared to commercial epoxy resins, and a decrease of approximately 10% in thermal degradation temperatures was observed.
A novel material for the deacidification and protection of paper has been designed by using MgO filled halloysite nanotubes (Hal). The ability of MgO loaded nanotubes to control the acidic conditions ...was evaluated by pH measurements in aqueous solvent. Afterwards, paper was impregnated into hydroxypropyl cellulose dispersions containing the consolidating material. A simulation of strong acidic conditions allowed us to evaluate the deacidification effect of the composite material on the samples. In particular, the paper reaches a pH of 7.7 after 1 h exposition to HNO3 vapours when MgO-Hal nanoparticles are added to the impregnation mixture at a concentration of 10 wt% and it remains still neutral after 12 h. Dynamic mechanical analysis showed that the tensile strength of the consolidated paper is improved, since the stress at breaking increase of ca. 8% for the samples treated with MgO-Hal compared to the untreated paper. Due to the presence of halloysite loaded with the alkaline reservoir, the acidic degradation of cellulose is neutralized as suggested by the stored energy which is similar to the pristine paper without any chemical attack. Therefore, the mechanical performances of the paper are preserved during the aging together with its macroscopic aspect, as suggested by colorimetric analysis. The proposed consolidation protocol represents a further step for the self-healing and long-term protection of cellulose based artworks.
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•MgO was loaded within halloysite nanotubes (Hal) by electrostatic interactions.•Paper was treated using hydroxypropyl cellulose/MgO-Hal aqueous dispersions.•MgO-Hal act as deacidifying fillers of cellulose.•The morphology, pH and tensile properties of the treated paper were investigated.•Treatment by 10 wt% MgO-Hal provides a paper protection from acidic aging.
The aim of this study is the design and preparation of Mater-Bi/halloysite nanocomposite materials that could be employed as bioplastics alternative to the petroleum derived products. The ...biocomposite materials at variable halloysite content (from 0 to 30 wt%) were prepared by using the solvent casting method. We investigated the mechanical behaviour and the thermal properties of the prepared nanocomposites in order to estimate their suitability as biocompatible packaging materials. The thermo-mechanical characteristics were correlated to the nanocomposites' morphologies, which were studied by Scanning Electron Microscopy (SEM). As a general result, the physico-chemical performances of Mater-Bi were improved by the presence of small amounts of nanotubes, which evidenced a homogenous distribution in the polymer matrix. The strongest enhancements of the thermal stability and tensile properties were achieved for Mater-Bi/halloysite 10 wt%. A further addition of nanotubes determined the worsening of both thermal stability and mechanical behaviour.
The attained knowledge represents the starting step for the development of packaging films composed by Mater-Bi and halloysite nanotubes.
•Mater-Bi/halloysite nanocomposite films with variable filler content were prepared by casting methods•The thermal and mechanical properties of the nanocomposites were affected by their specific composition•Mater-Bi/halloysite 10 wt% evidenced the most promising performances in agreement with its uniformity•Mater-Bi/halloysite 30 wt% exhibited lower mechanical and thermal performances respect to pure Mater-Bi
Oxidized organic molecules from ozonolysis of α-pinene are believed to participate in atmospheric new particle formation in forest regions. However, the detailed process of nucleation originated from ...α-pinene ozonolysis remains unclear. In this study, an atmospheric pressure interface time-of-flight mass spectrometer coupled with a planar differential mobility analyzer (DMA-MS) was applied to investigate the gas-phase reaction of α-pinene and ozone. Ion mobility and mass to charge ratio of the oxidized molecules were simultaneously measured. The ion mobility distribution of these oxidation products highlighted three mobility diameter ranges: 0.89–0.99 nm, 1.16–1.24 nm and 1.31–1.38 nm, where the dominating molecules were CH2O2, C7-10H10-20O3-7 and C19-20H30-32O6-9, respectively. Combining the DMA-MS measurements, quantum chemistry calculations, and ion mobility modeling, the dominant monomer (C10H16O3) was confirmed as pinonic acid while the primary dimer (C20H32O6) was considered as pinonic acid cluster ((C10H16O3)2). Considering the yield of pinonic acid produced from α-pinene ozonolysis (2–4%), (C10H16O3)2 potentially accounts for part of the nocturnal C20 dimers and ungrowable sub-2-nm particles in forests. Our work provides a new method to facilitate the understanding of atmospheric nucleation and initial growth.
•A novel method to characterize molecular structures is introduced.•The dominating products of α-pinene ozonolysis are confirmed to be organic acid molecules and clusters.•Pinonic acid cluster potentially accounts for part of the nocturnal C20 dimers and ungrowable sub-2-nm particles in forests.
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