Additional XPS Studies on the Degradation of Poly(Methyl Methacryalte) and Polystyrene Nanocomposites

XPS studies have been undertaken on exfoliated nanocomposites of polystyrene and poly(methyl methacrylate). One can clearly see that carbon is lost and that oxygen, silicon and aluminum accumulate at the surface of the degrading polymer. The concentration of aluminum at the surface is very low at the beginning of the experiment but makes a large jump at the same temperature at which carbon is lost and oxygen begins to accumulate at the surface. It appears that the ratio of silicon to aluminum changes as the polymer is lost. A brief discussion is given to explain the origin of oxygen at the surface

Direct single-molecule dynamic detection of chemical reactions.

Single-molecule detection can reveal time trajectories and reaction pathways of individual intermediates/transition states in chemical reactions and biological processes, which is of fundamental importance to elucidate their intrinsic mechanisms. We present a reliable, label-free single-molecule approach that allows us to directly explore the dynamic process of basic chemical reactions at the single-event level by using stable graphene-molecule single-molecule junctions. These junctions are constructed by covalently connecting a single molecule with a 9-fluorenone center to nanogapped graphene electrodes. For the first time, real-time single-molecule electrical measurements unambiguously show reproducible large-amplitude two-level fluctuations that are highly dependent on solvent environments in a nucleophilic addition reaction of hydroxylamine to a carbonyl group. Both theoretical simulations and ensemble experiments prove that this observation originates from the reversible transition between the reactant and a new intermediate state within a time scale of a few microseconds. These investigations open up a new route that is able to be immediately applied to probe fast single-molecule physics or biophysics with high time resolution, making an important contribution to broad fields beyond reaction chemistry

Towards Better Multi-modal Keyphrase Generation via Visual Entity Enhancement and Multi-granularity Image Noise Filtering

Multi-modal keyphrase generation aims to produce a set of keyphrases that represent the core points of the input text-image pair. In this regard, dominant methods mainly focus on multi-modal fusion for keyphrase generation. Nevertheless, there are still two main drawbacks: 1) only a limited number of sources, such as image captions, can be utilized to provide auxiliary information. However, they may not be sufficient for the subsequent keyphrase generation. 2) the input text and image are often not perfectly matched, and thus the image may introduce noise into the model. To address these limitations, in this paper, we propose a novel multi-modal keyphrase generation model, which not only enriches the model input with external knowledge, but also effectively filters image noise. First, we introduce external visual entities of the image as the supplementary input to the model, which benefits the cross-modal semantic alignment for keyphrase generation. Second, we simultaneously calculate an image-text matching score and image region-text correlation scores to perform multi-granularity image noise filtering. Particularly, we introduce the correlation scores between image regions and ground-truth keyphrases to refine the calculation of the previously-mentioned correlation scores. To demonstrate the effectiveness of our model, we conduct several groups of experiments on the benchmark dataset. Experimental results and in-depth analyses show that our model achieves the state-of-the-art performance. Our code is available on https://github.com/DeepLearnXMU/MM-MKP.Comment: Accepted In Proceedings of the 31st ACM International Conference on Multimedia (MM' 23

Iron and zinc binding activity of Escherichia coli topoisomerase I homolog YrdD

YrdD, a homolog of the C-terminal zinc-binding region of Escherichia coli topoisomerase I, is highly conserved among proteobacteria and enterobacteria. However, the function of YrdD remains elusive. Here we report that YrdD purified from E. coli cells grown in LB media contains both zinc and iron. Supplement of exogenous zinc in the medium abolishes the iron binding of YrdD in E. coli cells, indicating that iron and zinc may compete for the same metal binding sites in the protein. While the zinc-bound YrdD is able to bind single-stranded (ss) DNA and protect ssDNA from the DNase I digestion in vitro, the iron-bound YrdD has very little or no binding activity for ssDNA, suggesting that the zinc-bound YrdD may have an important role in DNA repair by interacting with ssDNA in cells. © 2014 Springer Science+Business Media

Lithosphere thinning beneath west North China Craton: Evidence from geochemical and Sr-Nd-Hf isotope compositions of Jining basalts

This study shows lithosphere evolution history in the west North China Craton (NCC) from the early Cretaceous to Quaternary by studying the major element, trace element and Sr-Nd-Hf isotope compositions in Jining basalts of 119.6-108.6. Ma, 23.5-21.9. Ma and 1.3-0.11. Ma.The early Cretaceous basalts (119.6-108.6Ma) display enriched characteristics with high contents of incompatible elements, high 87Sr/86Sri, low εNd(t) and low εHf(t). These basalts resulted from partial melting of ancient metasomatized lithospheric mantle, and we consider the 119.6-108.6Ma magmatism as indicating lithosphere thinning in the west NCC. Although the Pacific slab seen seismically in the mantle transition zone beneath eastern China is no older than 60Ma, there exists convincing evidence for the presence of the Paleo-Pacific slab in the transition-zone in the Mesozoic. Thus we propose that the water released from the transition-zone slab hydrated the overlying lithosphere and further converted the base of the lithosphere into asthenosphere. This is the most likely mechanism responsible for the lithosphere thinning in the west NCC and the petrogenesis of the Jining 119.6-108.6Ma basalts.The Jining 23.5-21.9Ma basalts also have high contents of incompatible elements, but they display high εNd(t), high εHf(t) and variably low 87Sr/86Sri. We propose that these Miocene basalts were derived from the asthenosphere with contributions from ancient metasomatized lithospheric mantle during melt ascent. The Jining Quaternary basalts (1.3-0.11Ma) represent the melt of upwelling asthenosphere with low 87Sr/86Sri, high εNd(t) and high εHf(t). Upwelling and decompression melting of the eastward flowing asthenosphere from beneath western plateaus to beneath eastern hilly plains in the Cenozoic is the most plausible mechanism for the petrogenesis of Jining Cenozoic basalts (both of 23.5-21.9Ma and 1.3-0.11Ma), but the Jining 1.3-0.11Ma basalts must have been produced beneath even thinner lithosphere.Taken together geophysical studies and our petrological and geochemical studies of all these three episodes of the Jining basalts, we propose that the lithosphere in the west NCC has been thinning since the early Cretaceous and the thinning continues to the present

Inertia matching of CNC cycloidal gear form grinding machine servo system

Reasonable ratio between the load inertia and servo motor inertia plays a decisive role for the dynamic performance and stability of the servo system, as well as the machining accuracy of the whole CNC machine. In order to improve the control performance and contour machining accuracy of the servo system of the CNC cycloidal gear form grinding machine, an optimization design method of the inertia matching for the CNC cycloidal gear form grinding machine servo system is proposed. The two-mass servo driving closed-loop PID control system is constructed, the influence of the different inertia ratios on the dynamic performance and contour errors of the servo system are deeply analyzed, and the inertia ratio is optimized to satisfied with the servo system performance requirements. Finally, the feasibility and practicability of the optimization design method of inertia matching are verified through the inertia ratio optimization grinding experiments of the cycloid gear in the CNC gear form grinding machine. This inertia matching optimization design method provides a valuable reference for the further design of CNC machine servo system

Characteristics and metabolic potential of biliary microbiota in patients with giant common bile duct stones

BackgroundEndoscopic retrograde cholangiopancreatography (ERCP) is an effective minimally invasive operation for the management of choledocholithiasis, while successful extraction is hampered by large diameter of stones. Emerging studies have revealed the close correlation between biliary microbiota and common bile duct stones (CBDS). In this study, we aimed to investigate the community characteristics and metabolic functions of biliary microbiota in patients with giant CBDS.MethodsEligible patients were prospectively enrolled in this study in First Affiliated Hospital of Soochow University from February 2022 to October 2022. Bile samples were collected through ERCP. The microbiota was analyzed using 16S rRNA sequencing. Metabolic functions were predicted by PICRUSTs 2.0 calculation based on MetaCyc database. Bile acids were tested and identified using ultra performance liquid chromatography-tandem mass spectrometry.ResultsA total of 26 patients were successfully included into final analysis, 8 in giant stone (GS) group and 18 in control group. Distinct biliary microbial composition was identified in patients with giant CBDS, with a significantly higher abundance of Firmicutes at phylum level. The unique composition at genus level mainly consisted of Enterococcus, Citrobacter, Lactobacillus, Pyramidobacter, Bifidobacterium and Shewanella. Pyramidobacter was exclusively found in GS group, along with the absence of Robinsoniella and Coprococcus. The contents of free bile acids were significantly higher in GS group, including cholic acid (98.39μmol/mL vs. 26.15μmol/mL, p=0.035), chenodesoxycholic acid (54.69μmol/mL vs. 5.86μmol/mL, p=0.022) and ursodeoxycholic acid (2.70μmol/mL vs. 0.17μmol/mL, p=0.047). Decreasing tendency of conjugated bile acids were also observed. Metabolic pathways concerning cholelithiasis were abundant in GS group, including geranylgeranyl diphosphate biosynthesis, gluconeogenesis, glycolysis and L-methionine biosynthesis.ConclusionsThis study demonstrated the community structure and metabolic potential of biliary microbiota in patients with giant CBDS. The unique biliary microbial composition holds valuable predictive potential for clinical conditions. These findings provide new insights into the etiology of giant CBDS from the perspective of biliary microbiota