Progress in process parameters and mechanism research of polymer emulsion preparation.

As a new type of concrete admixture, polymer emulsion is mainly used to strengthen the properties of concrete by adhesion and physical and chemical crosslinking with cement in concrete. Under the background of construction in the new era, it is of great significance to elucidate all aspects of concrete performance under the action of polymer emulsion. In this paper, the main formation process of polymer emulsion is reviewed, the influence of synthetic materials required for polymerization on the polymerization process is discussed, and the regulating effects of reaction temperature, reaction time, admixtures, and treatment methods on the synthesis process of polymer emulsion are analyzed. The action mechanism of polymer emulsion on concrete was deeply investigated, and the synthesis method was studied to provide an important experimental and theoretical basis for the preparation of new emulsion materials and the process of emulsion polymerization. The problems of polymer emulsion raw materials, synthetic conditions, and synthetic methods are introduced. The future development trend of polymer emulsion is predicted and the future research ideas are put forward.

Synthesis and Modification of Polycarboxylate Superplasticizers-A Review.

The molecular-scale structural changes in polycarboxylic superplasticizer (PCE) can influence dispersion and water retention. Polycarboxylate superplasticizer, synthesized using different methods, may alter dispersion and water-reducing effects. The synthesis of PCE involves creating a novel macromolecular monomer with a controllable molecular mass, adjustable lipophilic, and hydrophilic moieties, as outlined in this study. This article reviews processes for synthesizing polycarboxylates and identifies the optimal method through orthogonal experiments to produce a modified polycarboxylate superplasticizer (PCE-P). The study investigated the effects of different PCE types and concentrations on the surface tension, fluidity, and ζ potential of cement paste. PCE-P, synthesized at room temperature, showed comparable performances in initial hydration and conversion rate in cement to PCE synthesized at high temperatures. PCE-P exhibited an increased slump but had a wider molecular weight distribution and longer main and side chains, leading to a 24.04% decrease in surface tension, indicating a good dispersibility.

Paternal chromosome elimination of inducer triggers induction of double haploids in Brassica napus.

A synthetic octoploid rapeseed, Y3380, induces maternal doubled haploids when used as a pollen donor to pollinate plant. However, the mechanism underlying doubled haploid formation remains elusive. We speculated that double haploid induction occurs as the inducer line's chromosomes pass to the maternal egg cell, and the zygote is formed through fertilization. In the process of zygotic mitosis, the paternal chromosome is specifically eliminated. Part of the paternal gene might have infiltrated the maternal genome through homologous exchange during the elimination process. Then, the zygote haploid genome doubles (early haploid doubling, EH phenomenon), and the doubled zygote continues to develop into a complete embryo, finally forming doubled haploid offspring. To test our hypothesis, in the current study, the octoploid Y3380 line was back bred with the 4122-cp4-EPSPS exogenous gene used as a marker into hexaploid Y3380-cp4-EPSPS as paternal material to pollinate three different maternal materials. The fertilization process of crossing between the inducer line and the maternal parent was observed 48 h after pollination, and the fertilization rate reached 97.92% and 98.72%. After 12 d of pollination, the presence of cp4-EPSPS in the embryo was detected by in situ PCR, and at 13-23 d after pollination, the probability of F1 embryos containing cp4-EPSPS gene was up to 97.27%, but then declined gradually to 0% at 23-33 d. At the same time, the expression of cp4-EPSPS was observed by immunofluorescence in the 3rd to 29th day embryo. As the embryos developed, cp4-EPSPS marker genes were constantly lost, accompanied by embryonic death. After 30 d, the presence of cp4-EPSPS was not detected in surviving embryos. Meanwhile, SNP detection of induced offspring confirmed the existence of double haploids, further indicating that the induction process was caused by the loss of specificity of the paternal chromosome. The tetraploid-induced offspring showed infiltration of the induced line gene loci, with heterozygosity and homozygosity. Results indicated that the induced line chromosomes were eliminated during embryonic development, and the maternal haploid chromosomes were synchronously doubled in the embryo. These findings support our hypothesis and lay a theoretical foundation for further localization or cloning of functional genes involved in double haploid induction in rapeseed.

Investigation of the Effects of Polyurethane-Modified Polycarboxylate at Ambient Temperature on the Characteristics of Cement with Supplementary Cementitious Materials.

Via radical polymerization, three polyurethane-modified polycarboxylate molecules of various comb topologies were synthesized. This study investigated the effects of varying types and concentrations of supplementary cementitious materials (SCMs) on the surface tension, flowability, and zeta potential of cement. An elevation in the molar ratio between isoamyl alcohol polyoxyethylene (TPEG) and acrylic acid (AA) from 1:1 to 5:1 reduced the surface tension of the polycarboxylate molecule from 47.70 mN/m to 35.53 mN/m and increased flowability from 280 mm to 310 mm, as the results indicated. An increase in the SCM and polycarboxylate dosage proportionally decreased liquid-phase surface tension and increased flowability. A decrease in the water-to-cement (w/c) ratio from 0.5 to 0.3 corresponded to an observed increase in the zeta potential of cement pastes. However, a rise in the quantity of polycarboxylate and SCMs corresponded to a decrease in the zeta potential at a w/c ratio of 0.3.

Context-Aware Multi-Scale Aggregation Network for Congested Crowd Counting.

In this paper, we propose a context-aware multi-scale aggregation network named CMSNet for dense crowd counting, which effectively uses contextual information and multi-scale information to conduct crowd density estimation. To achieve this, a context-aware multi-scale aggregation module (CMSM) is designed. Specifically, CMSM consists of a multi-scale aggregation module (MSAM) and a context-aware module (CAM). The MSAM is used to obtain multi-scale crowd features. The CAM is used to enhance the extracted multi-scale crowd feature with more context information to efficiently recognize crowds. We conduct extensive experiments on three challenging datasets, i.e., ShanghaiTech, UCF_CC_50, and UCF-QNRF, and the results showed that our model yielded compelling performance against the other state-of-the-art methods, which demonstrate the effectiveness of our method for congested crowd counting.

Genetic characteristics and ploidy trigger the high inducibility of double haploid (DH) inducer in Brassica napus.

BACKGROUND: Our recently reported doubled haploid (DH) induction lines e.g., Y3380 and Y3560 are allo-octoploid (AAAACCCC, 2n = 8× ≈ 76), which can induce the maternal parent to produce DH individuals. Whether this induction process is related to the production of aneuploid gametes form male parent and genetic characteristics of the male parent has not been reported yet. RESULTS: Somatic chromosome counts of DH inducer parents, female wax-less parent (W1A) and their F1 hybrid individuals revealed the reliability of flow cytometry analysis. Y3560 has normal chromosome behavior in metaphase I and anaphase I, but chromosome division was not synchronized in the tetrad period. Individual phenotypic identification and flow cytometric fluorescence measurement of F1 individual and parents revealed that DH individuals can be distinguished on the basis of waxiness trait. The results of phenotypic identification and flow cytometry can identify the homozygotes or heterozygotes of F1 generation individuals. The data of SNP genotyping coupled with phenotypic waxiness trait revealed that the genetic distance between W1A and F1 homozygotes were smaller as compared to their heterozygotes. It was found that compared with allo-octoploids, aneuploidy from allo-octoploid segregation did not significantly increase the DH induction rate, but reduced male infiltration rate and heterozygous site rate of induced F1 generation. The ploidy, SNP genotyping and flow cytometry results cumulatively shows that DH induction is attributed to the key genes regulation from the parents of Y3560 and Y3380, which significantly increase the induction efficiency as compared to ploidy. CONCLUSION: Based on our findings, we hypothesize that genetic characteristics and aneuploidy play an important role in the induction of DH individuals in Brassca napus, and the induction process has been explored. It provides an important insight for us to locate and clone the genes that regulate the inducibility in the later stage.

DNA repair- and nucleotide metabolism-related genes exhibit differential CHG methylation patterns in natural and synthetic polyploids (Brassica napus L.).

Polyploidization plays a crucial role in the evolution of angiosperm species. Almost all newly formed polyploids encounter genetic or epigenetic instabilities. However, the molecular mechanisms contributing to genomic instability in synthetic polyploids have not been clearly elucidated. Here, we performed a comprehensive transcriptomic and methylomic analysis of natural and synthetic polyploid rapeseeds (Brassica napus). Our results showed that the CHG methylation levels of synthetic rapeseed in different genomic contexts (genes, transposon regions, and repeat regions) were significantly lower than those of natural rapeseed. The total number and length of CHG-DMRs between natural and synthetic polyploids were much greater than those of CG-DMRs and CHH-DMRs, and the genes overlapping with these CHG-DMRs were significantly enriched in DNA damage repair and nucleotide metabolism pathways. These results indicated that CHG methylation may be more sensitive than CG and CHH methylation in regulating the stability of the polyploid genome of B. napus. In addition, many genes involved in DNA damage repair, nucleotide metabolism, and cell cycle control were significantly differentially expressed between natural and synthetic rapeseeds. Our results highlight that the genes related to DNA repair and nucleotide metabolism display differential CHG methylation patterns between natural and synthetic polyploids and reveal the potential connection between the genomic instability of polyploid plants with DNA methylation defects and dysregulation of the DNA repair system. In addition, it was found that the maintenance of CHG methylation in B. napus might be partially regulated by MET1. Our study provides novel insights into the establishment and evolution of polyploid plants and offers a potential idea for improving the genomic stability of newly formed Brassica polyploids.

Congested Crowd Counting via Adaptive Multi-Scale Context Learning.

In this paper, we propose a novel congested crowd counting network for crowd density estimation, i.e., the Adaptive Multi-scale Context Aggregation Network (MSCANet). MSCANet efficiently leverages the spatial context information to accomplish crowd density estimation in a complicated crowd scene. To achieve this, a multi-scale context learning block, called the Multi-scale Context Aggregation module (MSCA), is proposed to first extract different scale information and then adaptively aggregate it to capture the full scale of the crowd. Employing multiple MSCAs in a cascaded manner, the MSCANet can deeply utilize the spatial context information and modulate preliminary features into more distinguishing and scale-sensitive features, which are finally applied to a 1 × 1 convolution operation to obtain the crowd density results. Extensive experiments on three challenging crowd counting benchmarks showed that our model yielded compelling performance against the other state-of-the-art methods. To thoroughly prove the generality of MSCANet, we extend our method to two relevant tasks: crowd localization and remote sensing object counting. The extension experiment results also confirmed the effectiveness of MSCANet.

Maternal karyogene and cytoplasmic genotype affect the induction efficiency of doubled haploid inducer in Brassica napus.

BACKGROUND: Artificial synthesis of octoploid rapeseed double haploid (DH) induction lines Y3380 and Y3560 was made possible by interspecific hybridization and genome doubling techniques. Production of pure lines by DH induction provides a new way to achieve homozygosity earlier in B.napus. Previously, the mechanism of induction, and whether the induction has obvious maternal genotypic differences or not, are not known so far. RESULTS: In this study, different karyogene and cytoplasmic genotype of B.napus were pollinated with the previously reported DH inducers e.g. Y3380 and Y3560. Our study presents a fine comparison of different cytoplasmic genotypes hybridization to unravel the mechanism of DH induction. Ploidy identification, fertility and SSR marker analysis of induced F1 generation, revealed that ploidy and phenotype of the induced F1 plants were consistent with that type of maternal, rather than paternal parent. The SNP chip analysis revealed that induction efficiency of DH inducers were affected by the karyogene when the maternal cytoplasmic genotypes were the same. However, DH induction efficiency was also affected by cytoplasmic genotype when the karyogenes were same, and the offspring of the ogura cytoplasm showed high frequency inducer gene hybridization or low-frequency infiltration. CONCLUSION: The induction effect is influenced by the interaction between maternal karyogene and cytoplasmic genotype, and the results from the partial hybridization of progeny chromosomes indicate that the induction process may be attributed to the selective elimination of paternal chromosome. This study provides a basis for exploring the mechanism of DH inducer in B.napus, and provides new insights for utilization of inducers in molecular breeding.

Genome-Wide Duplication of Allotetraploid Brassica napus Produces Novel Characteristics and Extensive Ploidy Variation in Self-Pollinated Progeny.

Whole genome duplications (WGDs) have played a major role in angiosperm species evolution. Polyploid plants have undergone multiple cycles of ancient WGD events during their evolutionary history. However, little attention has been paid to the additional WGD of the existing allopolyploids. In this study, we explored the influences of additional WGD on the allopolyploid Brassica napus Compared to tetraploid B. napus, octoploid B. napus (AAAACCCC, 2n = 8x =76) showed significant differences in phenotype, reproductive ability and the ploidy of self-pollinated progeny. Genome duplication also altered a key reproductive organ feature in B. napus, that is, increased the number of pollen apertures. Unlike autopolyploids produced from the diploid Brassica species, the octoploid B. napus produced from allotetraploid B. napus had a relatively stable meiotic process, high pollen viability and moderate fertility under self-pollination conditions, indicating that sub-genomic interactions may be important for the successful establishment of higher-order polyploids. Doubling the genome of B. napus provided us with an opportunity to gain insight into the flexibility of the Brassica genomes. The genome size of self-pollinated progeny of octoploid B. napus varied greatly, and was accompanied by extensive genomic instability, such as aneuploidy, mixed-ploidy and mitotic abnormality. The octoploid B. napus could go through any of genome reduction, equilibrium or expansion in the short-term, thus providing a novel karyotype library for the Brassica genus. Our results reveal the short-term evolutionary consequences of recurrent polyploidization events, and help to deepen our understanding of polyploid plant evolution.

[Efficiency of Magnesium Hydroxide Capping and Amendment to Control Phosphorus Release from Sediments].

Eutrophication of freshwater bodies has become a global environmental problem, and phosphorus (P) has been identified as one of the key limiting factors responsible for this eutrophication problem. Reducing internal P release is crucial to the control of the eutrophication of freshwater bodies besides reducing the input of external P. To control sedimentary P release, magnesium hydroxide[Mg(OH)2] was applied as a capping and amendment material in this study. The adsorption performance of phosphate on Mg(OH)2 was investigated in batch mode, and the effect of Mg(OH)2 capping and amendment on the mobilization of P in sediments was studied using sediment incubation experiments. Results showed that Mg(OH)2 exhibited good adsorption performance toward phosphate. The phosphate removal efficiency of Mg(OH)2 increased with increasing adsorbent dosage. The adsorption equilibrium data of phosphate on Mg(OH)2 could be better described by the Freundlich and Dubinin-Radushkevich isotherm models compared to the Langmuir isotherm model. Mg(OH)2 capping and addition both could effectively control the release of reactive soluble P (SRP) from sediments into the overlying water, resulting in a low concentration of SRP in the overlying water under Mg(OH)2 capping and amendment conditions. Mg(OH)2 capping and amendment both could reduce pore water SRP in the uppermost sediment (0-10 mm), which played a key role in the control of the release of SRP from sediments into the overlying water. The as-prepared Mg(OH)2 possessed a much higher phosphate adsorption ability than commercial Mg(OH)2, and the former also had a higher controlling efficiency of sedimentary P release than the latter. In summary, Mg(OH)2 is a promising capping and amendment material for the control of internal phosphorus release in freshwater bodies.

[Regulating Effect and Mechanism of Calcite/Chlorapatite Mixture Addition on Transformation and Transport of Phosphorus in Sediments].

Understanding the effect of calcite and chlorapatite mixture (CA/ClAP) addition on the mobilization of phosphorus (P) in sediments is crucial to the application of CA/ClAP as an amendment material to control the release of P from sediments. To address this issue, batch experiments were conducted to investigate the removal performance of phosphate by CA/ClAP, and sediment incubation experiments were carried out to study the effect of CA/ClAP addition on the mobilization of P in sediments. The results showed that the removal ability of phosphate by CA/ClAP was much higher than those by calcite and chlorapatite, and the kinetics data of phosphate removal by CA/ClAP followed a pseudo-second-order kinetics model. Increasing calcite and chlorapatite dosages would be favorable for the removal of phosphate by CA/ClAP, and coexisting Ca2+ enhanced the phosphate removal. CA/ClAP addition not only reduced the concentration of soluble reactive P (SRP) in the overlying water, but also decreased the concentration of SRP in the pore water. The addition of CA/ClAP in sediments caused an increase in the content of P in the sediments, but the increased P mainly existed in the form of calcium-bound P (HCl-P), which was difficult to be re-released into the water column under anoxic and common pH (5-9) conditions. The reduction of SRP in the pore water after the addition of CA/ClAP played an important role in the prevention of sedimentary P liberation into the overlying water by the CA/ClAP amendment. The results of this work indicate that CA/ClAP can be used as an amendment material for interception of the release of P from sediments into overlying water.