双马来酰亚胺/氰酸酯型发泡胶的制备与表征

以4,4’-双马来酰亚胺二苯甲烷(BMI-1)、双酚A型氰酸酯(BADCy)和酚酞型聚芳醚砜(PES-C)为原料通过加入发泡剂合成了双马来酰亚胺/氰酸酯耐高温发泡胶。通过差示扫描量热分析和红外表征分析了树脂的固化行为。扫描电子显微镜分析表明,该发泡胶发泡均匀细腻(平均泡孔直径0.275 mm)。热重分析结果表明,该发泡胶具有很高的耐温性:空气和氮气氛围下10%分解温度分别为393℃和412℃。发泡胶在9.375 GHz频率下的介电常数为1.65、介电损耗为0.0057,展现了优异的介电性能。管剪测试表明,该发泡胶具有优异的黏结性能和耐温性能,-55℃、25℃和150℃管剪强度均大于7 MPa,205℃管剪强度不小于4 MPa。与多种材料的拉伸测试结果表明,该发泡胶与多种材料具有优异的黏结性能,铝-铝拉伸强度为9.2 MPa、钛-钛拉伸强度为5.9 MPa、双马基复材-双马基复材拉伸强度为5.9 MPa。

Devonian integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

The Devonian System in the Qinghai-Tibetan Plateau and its surrounding areas is widely distributed,diverse in lithotypes and rich in fossils.It records the crucial processes of continuous subduction and reduction of the Paleo-Asian Ocean in the northern hemisphere and the transformation of the Proto-Tethys Ocean into the Paleo-Tethys Ocean in the southern hemisphere.Thus,it is of great significance for explaining the global paleogeographic evolution,tectonic activities and biodiversity changes during this critical period.The blocks on both sides of the southern Tienshan suture zone and the Longmu Co-ShuanghuChangning-Menglian suture zone belong to different sedimentary systems and paleobiogeographic realms and regions,showing important tectonic paleogeographic partitioning significance.The two suture zones represent the main branches of the PaleoAsian Ocean and the Paleo-Tethys Ocean,respectively,and on this basis the Devonian System can be subdivided into three types:the Tienshan type,the Tethys type and the Gondwana type.Based on recent research progress on the Devonian stratigraphy and paleontology in combining provenance analysis and biotic characteristics in the Qinghai-Tibetan Plateau and surrounding areas,this paper aims to establish the latest integrative stratigraphic framework and conduct paleogeographic reconstruction,providing foundation for exploring the geological evolution and dynamic mechanisms of various terranes and blocks in the northern margin of Gondwana.The results indicate that the North Qiangtang,South Qiangtang,Simao,Baoshan and Tengchong terranes,as well as the Himalaya Tethys Zone and the South China Block have affinities with the Indian Block,while the Lhasa Terrane has affinities with the Australian Block,and may be located between the South China and Australian blocks.In the Emsian(Early Devonian),the South China Block separated from the northern margin of Gondwana,a process that was accompanied by the opening of the Jinshajiang-Ailaoshan Ocean.In the Middle Devonian,the mid-oceanic ridge of the Paleo-Tethys Ocean expanded rapidly,corresponding with a global sea-level rise,the widespread development of carbonate platforms and nadir values of Devonian seawater strontium isotopes.By the Late Devonian,the Paleo-Tethys Ocean had reached a considerable size,leading to abundant occurrences of Upper Devonian radiolarian cherts in the Paleo-Tethys suture zones.

Devonian integrative stratigraphy and timescale of China

The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian stratigraphers include further subdivision of these standard stages, strictly constrained absolute ages for the boundaries, and precise neritic-pelagic and marine-terrestrial correlations using multidisciplinary stratigraphy methods. Establishment of high-resolution Devonian integrative stratigraphy framework and timescale of China would play an important role in improving regional and international correlation, facilitating the recognition of important stratigraphic levels in different paleogeographic settings, and understanding the evolution pattern of biota, paleoclimate and paleoenvironment during this critical interval. Based on well-studied bio-and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.Up to date, few studies have been conducted on the astronomical cyclostratigraphy and high-resolution radioactive isotope dating in Devonian of China, which should be our main focuses in the near future.

Carboniferous integrative stratigraphy and timescale of China

The Carboniferous period lasted about 60 Myr, from ～358.9 Ma to ～298.9 Ma. According to the International Commission on Stratigraphy, the Carboniferous System is subdivided into two subsystems, i.e., Mississippian and Pennsylvanian, including 6 series and 7 stages. The Global Stratotype Sections and Points(GSSPs) of three stages have been ratified, the Tournaisian, Visean, and Bashkirian stages. The GSSPs of the remaining four stages(i.e., the Serpukhovian, Moscovian,Kasimovian, and Gzhelian) have not been ratified so far. This paper outlines Carboniferous stratigraphic subdivision and correlation on the basis of detailed biostratigraphy mainly from South China, and summarizes the Carboniferous chronostratigraphic framework of China. High-resolution biostratigraphic study reveals 37 conodont zones, 24 foraminiferal(including fusulinid) zones, 13 ammonoid zones, 10 brachiopod zones, and 10 rugose coral zones in the Carboniferous of China. The biostratigraphic framework based on these biozones warrants the precise correlation of regional stratigraphy of China(including2 subsystems, 4 series, and 8 stages) to that of the other regions globally. Meanwhile, the Carboniferous chemo-, sequence-,cyclo-, and event-stratigraphy of China have been intensively studied and can also be correlated worldwide. Future studies on the Carboniferous in China should focus on(1) the correlation between shallow-and deep-water facies and between marine and continental facies,(2) high-resolution astronomical cyclostratigraphy, and(3) paleoenvironment and paleoclimate analysis based on geochemical proxies such as strontium and oxygen isotopes, as well as stomatal indices of fossil plants.

USP7 deubiquitinates and stabilizes NOTCH1 in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia(T-ALL)is a highly aggressive leukemia that is primarily caused by aberrant activation of the NOTCH1 signaling pathway.Recent studies have revealed that posttranslational modifications,such as ubiquitination,regulate NOTCH1 stability,activity,and localization.However,the specific deubiquitinase that affects NOTCH1 protein stability remains unestablished.Here,we report that ubiquitin-specific protease 7(USP7)can stabilize NOTCH1.USP7 deubiquitinated NOTCH1 in vivo and in vitro,whereas knockdown of USP7 increased the ubiquitination of NOTCH1.USP7 interacted with NOTCH1 protein in T-ALL cells,and the MATH and UBL domains of USP7 were responsible for this interaction.Depletion of USP7 significantly suppressed the proliferation of T-ALL cells in vitro and in vivo,accompanied by downregulation of the NOTCH1 protein level.Similarly,pharmacologic inhibition of USP7 led to apoptosis of T-ALL cells.More importantly,we found that USP7 was significantly upregulated in human T-ALL cell lines and patient samples,and a USP7 inhibitor exhibited cell cytotoxicity toward primary T-ALL cells,indicating the clinical relevance of these findings.Overall,our results demonstrate that USP7 is a novel deubiquitinase that stabilizes NOTCH1.Therefore,USP7 may be a promising therapeutic target in the currently incurable T-ALL.