Search

This study examines the mechanism of adsorption–dispersion by superplasticisers with varying side chain density in cement paste. Acrylic acid was used to copolymerise with 2-methylprop-2-ene polyethylene glycol, using chain transfer agent to synthesise polycarboxylate ether superplasticisers (PCEs) with comparable main chain lengths and different side chain densities. Gel permeation chromatography, zeta potential, total organic carbon and fluidity tests were used to investigate the adsorption–dispersion of PCE samples in cement pastes with different amounts of tricalcium aluminate (C3A) additive. The results indicate: products with higher side chain densities also have correspondingly shorter main chains, which allows them to form conformations with comparable initial adsorption performance; with C3A added, samples with denser side chains performed better, and their resistance to adsorption became more prominent at higher C3A content.

Additional file 1. Supplemental Materials.

Additional file 2. Supplemental Tables.

International audience; Barium germano-gallate (BGG) glasses are attractive glass hosts for photonic applications in the mid-infrared region up to 6 µm. In this work, we investigate the photosensitivity of such glasses under femtosecond laser, with an emphasize on the formation of refractive index changes. Six glasses with varying compositions (including addition of K, Na, Y, and La) were studied. We observed several transformation regimes in the pulse energyrepetition rate landscape: Type I (isotropic refractive index change) and a spatial broadening regime with a phase shift Δφ > 2π rad at 550 nm. This translates into refractive index changes Δn > 10-2 and is comparable to values obtained in most chalcogenide glasses. The effect of glass composition on Δφ appears correlated to the number of non-bridging oxygen (NBO) present in the glass and is brought to evidence by monitoring the Cations/GaO3/2 ratio. This provides a way to design a range of germano-gallate glasses suitable to imprinting high refractive index contrast.

Background Abscisic acid (ABA) is an important phytohormone for plant growth, development and responding to stresses such as drought, salinity, and pathogen infection. Pyrabactin Resistance 1 (PYR1)/PYR1-Like (PYL)/Regulatory Component of ABA Receptor (RCAR) (hereafter referred to as PYLs) has been identified as the ABA receptors. The PYL family members have been well studied in many plants. However, the members of PYL family have not been systematically identified at genome level in cultivated tobacco (Nicotiana tabacum) and its two ancestors. In this study, the phylogenic relationships, chromosomal distribution, gene structures, conserved motifs/regions, and expression profiles of NtPYLs were analyzed. Results We identified 29, 11, 16 PYLs in the genomes of allotetraploid N. tabacum, and its two diploid ancestors N. tomentosiformis and N. sylvestris, respectively. The phylogenetic analysis revealed that NtPYLs can be divided into three subfamilies, and each NtPYL has one counterpart in N. sylvestris or N. tomentosiformis. Based on microarray analysis of NtPYL transcripts, four NtPYLs (from subfamily II, III), and five NtPYLs (from subfamily I) are highlighted as potential candidates for further functional characterization in N. tabacum seed development, response to ABA, and germination, and resistance to abiotic stresses, respectively. Interestingly, the expression profiles of members in the same NtPYL subfamily showed somehow similar patterns in tissues at different developmental stages and in leaves of seedlings under drought stress, suggesting particular NtPYLs might have multiple functions in both plant development and drought stress response. Conclusions NtPYLs are highlighted for important functions in seed development, germination and response to ABA, and particular in drought tolerance. This work will not only shed light on the PYL family in tobacco, but also provides some valuable information for functional characterization of ABA receptors in N. tabacum. Electronic supplementary material The online version of this article (10.1186/s12864-019-5839-2) contains supplementary material, which is available to authorized users.

The TianQin Project is aiming at gravitational wave (GW) detection in space. TianQin GW observatory comprises three satellites orbiting on 1 × 105 km Earth orbits to form an equilateral-triangle constellation. In order to minimize the variations in arm lengths and breathing angles, the satellites must be launched and adjusted precisely into an optimized orbit. Therefore, satellite laser ranging must be used to enhance the precision of satellite orbit determination. To develop the capability of satellite laser ranging for TianQin’s orbit, the TianQin Laser Ranging Station has been designed and constructed to perform high-precision laser ranging for TianQin satellites and lunar laser ranging as well. Applying a 1064 nm Nd: YAG laser with 100 Hz repetition frequency, 80 pico-second pulse duration, and 2 × 2 array of superconducting nanowire single-photon detectors, we have obtained the laser echo signals from the five lunar retro-reflector arrays, and the measurement data have been packaged into 234 normal points (NPs), including a few data measured during the full-moon lunar phase. Each NP is calculated from continuous measurement for about ten minutes and the statistical error of the NPs is about 7 mm (1σ).

The effect of Ti and B microalloying on the hardenability, prior austenite grain size (PAGS), mechanical properties, and sulfide stress cracking (SSC) of C110 grade steel was studied by Jominy testing, static tensile testing, an optical microscope (OM), scanning electron microscopy (SEM) and double cantilever beam (DCB) testing. The results show that the addition of 0.015% Ti and 0.002% B into a medium-carbon Fe-Cr-Mo-Nb-V steel increased the hardenability and refined the PAGS and quenched martensite packets, and the size of carbides was reduced. It is believed that these behaviors are responsible for the improvement in the threshold stress intensity factor KISSC.

In this paper, a novel perceptual image hashing scheme for color images is proposed based on ring-ribbon quadtree and color vector angle. First, original image is subjected to normalization and Gaussian low-pass filtering to produce a secondary image, which is divided into a series of ring-ribbons with different radii and the same number of pixels. Then, both textural and color features are extracted locally and globally. Quadtree decomposition (QD) is applied on luminance values of the ring-ribbons to extract local textural features, and the gray level co-occurrence matrix (GLCM) is used to extract global textural features. Local color features of significant corner points on outer boundaries of ring-ribbons are extracted through color vector angles (CVA), and color low-order moments (CLMs) is utilized to extract global color features. Finally, two types of feature vectors are fused via canonical correlation analysis (CCA) to prodcue the final hash after scrambling. Compared with direct concatenation, the CCA feature fusion method improves classification performance, which better reflects overall correlation between two sets of feature vectors. Receiver operating characteristic (ROC) curve shows that our scheme has satisfactory performances with respect to robustness, discrimination and security, which can be effectively used in copy detection and content authentication.

Visual noise is often regarded as a disturbance in image quality, whereas it can also provide a crucial clue for image-based forensic tasks. Conventionally, noise is assumed to comprise an additive Gaussian model to be estimated and then used to reveal anomalies. However, for real sensor noise, it should be modeled as signal-dependent noise (SDN). In this work, we apply SDN to splicing forgery localization tasks. Through statistical analysis of the SDN model, we assume that noise can be modeled as a Gaussian approximation for a certain brightness and propose a likelihood model for a noise level function. By building a maximum a posterior Markov random field (MAP-MRF) framework, we exploit the likelihood of noise to reveal the alien region of spliced objects, with a probability combination refinement strategy. To ensure a completely blind detection, an iterative alternating method is adopted to estimate the MRF parameters. Experimental results demonstrate that our method is effective and provides a comparative localization performance.