We present a study of ultra-diffuse galaxies (UDGs) in the Virgo Cluster based on deep imaging from the Next Generation Virgo Cluster Survey. Applying a new definition for the UDG class based on galaxy scaling relations, we define samples of 44 and 26 UDGs using expansive and restrictive selection criteria, respectively. Our UDG sample includes objects that are significantly fainter than previously known UDGs: i.e., more than half are fainter than mag arcsec−2. The UDGs in Virgo’s core region show some evidence for being structurally distinct from “normal” dwarf galaxies, but this separation disappears when considering the full sample of galaxies throughout the cluster. UDGs are more centrally concentrated in their spatial distribution than other Virgo galaxies of similar luminosity, while their morphologies demonstrate that at least some UDGs owe their diffuse nature to physical processes—such as tidal interactions or low-mass mergers—that are at play within the cluster environment. The globular cluster (GC) systems of Virgo UDGs have a wide range in specific frequency (S N ), with a higher mean S N than “normal” Virgo dwarfs, but a lower mean S N than Coma UDGs at fixed luminosity. Their GCs are predominantly blue, with a small contribution from red clusters in the more massive UDGs. The combined GC luminosity function is consistent with those observed in dwarf galaxies, showing no evidence of being anomalously luminous. The diversity in their morphologies and their GC properties suggests no single process has given rise to all objects within the UDG class. Based on the available evidence, we conclude that UDGs are simply those systems that occupy the extended tails of the galaxy size and surface brightness distributions.

It has long been speculated that many starburst or compact dwarf galaxies are resulted from dwarfdwarf galaxy merging, but unequivocal evidence for this possibility has rarely been reported in the literature. We present the first study of deep optical broadband images of a gas-dominated blue compact dwarf galaxy (BCD) VCC848 (M 2×10 8 M ) which hosts extended stellar shells and thus is confirmed to be a dwarf-dwarf merger. VCC848 is located in the outskirts of the Virgo Cluster. By analyzing the stellar light distribution, we found that VCC848 is the result of a merging between two dwarf galaxies with a primary-to-secondary mass ratio 5 for the stellar components and 2 for the presumed dark matter halos. The secondary progenitor galaxy has been almost entirely disrupted. The age-mass distribution of photometrically selected star cluster candidates in VCC848 implies that the cluster formation rate (CFR, ∝ star formation rate) was enhanced by a factor of ∼ 7 − 10 during the past ∼ 1 Gyr. The merging-induced enhancement of CFR peaked near the galactic center a few hundred Myr ago and has started declining in the last few tens of Myr. The current star formation activities, as traced by the youngest clusters, mainly occur at large galactocentric distances ( 1 kpc). The fact that VCC848 is still (atomic) gas-dominated after the period of most violent collision suggests that gas-rich dwarf galaxy merging can result in BCD-like remnants with extended atomic gas distribution surrounding a blue compact center, in general agreement with previous numerical simulations.

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Bismaleimide (BMI) resin is a high-performance thermosetting polymer, but its inherent brittleness hinder a broader range of application. Therefore, it has aroused wide concern to improve the toughness of BMI resins without scarification of their thermal stability. This paper reported some studies on modified BMI resins based on diallyl bisphenol A, novel BMI monomers, e.g. 2-[3-(4-maleimidophenoxy)phenyl]-5-(4-maleimidophenyl)-1,3,4-oxadiazole (m-Mioxd) or 2-[4-(4-maleimidophenoxy)phenyl]-5-(4-maleimidophenyl)-1,3,4-oxadiazole (p-Mioxd) in different proportions (0.87:1, 1:1, 1.2:1; mol/mol). The curing mechanism and kinetics of the copolymerized systems were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. Thermogravimetric analysis was applied to study the thermal properties of the cured resins, and the results indicated that the modified resins had excellent thermal stability with high residual weight percentage at 700°C (>50%), temperatures for 5% weight loss around 400°C. Besides, N,N′-4,4′-bismaleimidodiphenylmethylene and O,O′-diallyl bisphenol A resin blends were modified by m-Mioxd and p-Mioxd, respectively. We investigated the effects of mole concentration of m-Mioxd or p-Mioxd on the curing process, mechanical properties, fracture toughness, and heat resistance of the modified resins. The results revealed that the introduction of m-Mioxd and p-Mioxd could improve the impact property of the modified BMI resins. When their proportion was 0.07, the impact strength increased 123.8% and 108.3%, respectively. The novel chain-extended BMIs could reduce the crosslink density of cured resins and improve the brittleness effectively.

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Medical waste is one special kind of hazardous wastes. If mishandled, it could cause disease spread and secondary pollution of dioxin. China produced huge amount medical wastes due to large population. Through a decade, medical waste centralized disposal sector rapidly developed with both incineration and non-incineration technology. With fully consideration advanced foreign technology, a set of Best Available Technology system of China gradually formed suitable for Chinese national conditions. This article placed emphasis on best available technology system of medical wastes centralized incineration facilities, and analyzed the application of technique retrofit of medical wastes centralized incineration facilities incorporated with case study.

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