An XPS investigation of thermal degradation and charring on poly(vinyl chloride)–clay nanocomposites

More information concerning the thermal degradation and charring of nanocomposites of poly(vinyl chloride), dioctyl phthalate and clay has been obtained by the use of X-ray photoelectron spectroscopy and the acquisition of the carbon (C1s), chlorine (Cl2p), and oxygen (O1s) spectra. In the cases of polystyrene–clay and poly(methyl methacrylate)–clay nanocomposites, it has been shown that the clay migrates to the surface as the temperature is raised and the polymer degrades, thereby confirming the barrier properties as a mechanism by which these materials function. For PVC–clay nanocomposites the surface at high temperatures is dominated by carbon, and not the oxygen of the clay. The presence of the clay does retard the chain-stripping degradation of the PVC and the enhanced char formation accounts for the observation of enrichment of carbon

An XPS Investigation of Thermal degradation and Charring of Cross-linked Polyisoprene and Polychloroprene

Our interest in butadiene-containing polymers had led to an investigation of the thermal degradation of polyisoprene, PIP, and polychloroprene, PCP. The connection between cross-linking and thermal stability through an examination of PIP and PCP has been reported. Like the course of thermogravimetric analysis (TGA) the cross-linking and charring of polymers subjected to heat can also be experimentally observed as function of temperatures by the pseudo-in-situ XPS (X-ray Photoelectron Spectroscopy). Data acquisition of C1s spectra as function of temperature permits us to explore: (1) the extent of cross-linking and/or carbon accumulation of systems of PCP and PIP with/without initiators, BPO and DCP, via the analysis of the relative intensity versus temperature; and (2) the onset of charring by determining the limiting transition temperature (LTGRL) of the graphite-like structure and particularly the plasmon loss (ΔEL)

Additional evidence for the migration of clay upon heating of clay–polypropylene nanocomposites from X-ray photoelectron spectroscopy (XPS)

The explanation for reduction in the peak heat release rate of polymer–clay nanocomposites which is normally accepted is that clay accumulates at the surface, forming a thermal shield which is also a barrier to mass transport. The process by which this clay arrives at the surface has never been described in print but the common assumption is that pyrolysis is required for clay accumulation to occur. In this work, X-ray photoelectron spectroscopy, a tool much more sensitive in surface analysis than conventional techniques, is used to probe the surface of polypropylene–clay nanocomposites that have been annealed at relatively low temperatures, well below that required for pyrolysis. The composition of the surface changes with time and temperature of annealing, which provide a strong indication that the clay at the surface undergoes chemical change at fairly low temperatures

mixed attention auto encoder for multi-class industrial anomaly detection

Most existing methods for unsupervised industrial anomaly detection train a separate model for each object category. This kind of approach can easily capture the category-specific feature distributions, but results in high storage cost and low training efficiency. In this paper, we propose a unified mixed-attention auto encoder (MAAE) to implement multi-class anomaly detection with a single model. To alleviate the performance degradation due to the diverse distribution patterns of different categories, we employ spatial attentions and channel attentions to effectively capture the global category information and model the feature distributions of multiple classes. Furthermore, to simulate the realistic noises on features and preserve the surface semantics of objects from different categories which are essential for detecting the subtle anomalies, we propose an adaptive noise generator and a multi-scale fusion module for the pre-trained features. MAAE delivers remarkable performances on the benchmark dataset compared with the state-of-the-art methods.Comment: 5 pages, 4 figure

An XPS Investigation of Thermal Degradation and Charring of PMMA Clay Nanocomposites

Poly(methyl methacrylate)–clay nanocomposites have been studied using X-ray photoelectron spectroscopy. It is clear that as the polymer undergoes thermal degradation, the clay accumulates at the surface and the barrier properties which result from this clay accumulation have been described as the reason for the decreased heat release rate for nanocomposites. The surface composition of the clay changes as the nanocomposite is heated and the changes are affected by the organic-modification that were applied to the clay in order to prepare the nanocomposite

XPS Characterization of Friedel-Crafts Cross-Linked Polystyrene

The combination of a difunctional alkylating agent, either hydroxymethylbenzyl chloride or α,α′-dichloroxylene with polystyrene or high-impact polystyrene together with a Friedel-Crafts catalyst, 2-ethylhexyldiphenylphosphate, and an amine to react with hydrogen chloride has been studied by X-ray photoelectron spectroscopy. The results confirm what had been suggested from previous investigations using thermogravimetric analysis; cross-linking of the polymer occurs as the temperature is raised and the alcohol-containing alkylating agent gives a greater amount of cross-linking than does the dichloro compound

Spatio-temporal variation and prediction of ecological quality based on remote sensing ecological index – a case study of Zhanjiang City, China

A significant portion of Zhanjiang City’s ecological land areas have been reduced as a result of the city’s growing urbanization, which has caused the city’s ecological environment quality to decline. In order to monitor the quality of the ecological environment, the remote sensing ecological index (RSEI) is frequently utilized. In this study, the Landsat series satellite images from 2000, 2005, 2009, 2015, and 2020 were used. The Normalized Differential Vegetation Index (NDVI), Wetness (WET), Normalized Differential Build-up and bare Soil Index (NDBSI), and Land Surface Temperature (LST) were the four indicators utilized in the RSEI to quantitatively evaluate the changes in ecological environment quality in Zhanjiang City. The results are as follows. (1) The mean RSEI values for the years 2000, 2005, 2009, 2015, and 2020 are, respectively, 0.579, 0.597, 0.597, 0.607, and 0.601. In addition, the overall ecological environment of Zhanjiang is very good. In terms of spatial differences, the ecological environment quality in the central and southeastern parts of Zhanjiang is significantly higher than that in other areas, while the ecological environment quality in its coastal town areas is much worse. The lower RSEI index of developed land in coastal areas proves that the RSEI index can reflect the deterioration of the urban environment in coastal areas from 2000 to 2020. Therefore, the RSEI can be used to evaluate the ecological environment quality of Zhanjiang City. (2) The ecological environment changes in the study area are “substantially better,” “better,” “no change,” “worse,” and “much worse,” respectively, according to the difference in RSEI processed between 2000 and 2020. These changes were 38.38, 6,047, 13.93, 6.65, and 34.58%. The percentage of ecological environmental quality in Zhanjiang City that has become better is higher than that has become worse. This indicates that the quality of ecological environment in Zhanjiang City has improved between 2000 and 2020. (3) The regression produced the following equation for the association, which was significant at the 0.053 level: 100*Rsei = 154.69–1.18*IS(R = 0.66). The remote sensing ecological index for Zhanjiang in 2035 is 0.488 when the city’s planned population and area are added together

Evolution by gene duplication of Medicago truncatula PISTILLATA-like transcription factors

[EN] PISTILLATA (PI) is a member of the B-function MADS-box gene family, which controls the identity of both petals and stamens in Arabidopsis thaliana. In Medicago truncatula (Mt), there are two PI-like paralogs, known as MtPI and MtNGL9. These genes differ in their expression patterns, but it is not known whether their functions have also diverged. Describing the evolution of certain duplicated genes, such as transcription factors, remains a challenge owing to the complex expression patterns and functional divergence between the gene copies. Here, we report a number of functional studies, including analyses of gene expression, protein-protein interactions, and reverse genetic approaches designed to demonstrate the respective contributions of each M. truncatula PI-like paralog to the B-function in this species. Also, we have integrated molecular evolution approaches to determine the mode of evolution of Mt PI-like genes after duplication. Our results demonstrate that MtPI functions as a master regulator of B-function in M. truncatula, maintaining the overall ancestral function, while MtNGL9 does not seem to have a role in this regard, suggesting that the pseudogenization could be the functional evolutionary fate for this gene. However, we provide evidence that purifying selection is the primary evolutionary force acting on this paralog, pinpointing the conservation of its biochemical function and, alternatively, the acquisition of a new role for this gene.This work was supported by grants from the Spanish Ministry of Economy and Competitiveness (MINECO; BIO2009-08134 and BIO2012-39849-CO2-01). MAF was supported by a grant from the MINECO (BFU2012-36346). We wish to thank Drs Santiago F. Elena Fito (IBMCP, CSIC-UPV), Jose V. Gimeno Alcaniz (IATA, CSIC), Javier Paz-Ares (CNB, CSIC), and Carlos Alonso-Blanco (CNB, CSIC) for valuable suggestions and comments in the initial stages of this work. The technical assistance of Rafael Martinez-Pardo in the greenhouse is gratefully acknowledged.Roque Mesa, EM.; Fares Riaño, MA.; Yenush, L.; Rochina Peñalver, MC.; Wen, J.; Mysore, KS.; Gómez Mena, MC.... (2016). Evolution by gene duplication of Medicago truncatula PISTILLATA-like transcription factors. Journal of Experimental Botany. 67(6):1805-1817. https://doi.org/10.1093/jxb/erv571S1805181767

Transcriptome analysis of secondary cell wall development in Medicago truncatula

This article describes a transcriptome microarray assay and high through-put quantitative real time PCR analysis of Medicago truncatula