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Manufacture and test of c/c-Sic sandwich structures

cEAS SPAcE JOURNAL 2020年第1期12卷 73-84页

作者： Heidenreich, Bernhard Bamsey, Nathan Shi, Yuan Such-Taboada, Miguel Koch, Dietmar DLR Inst Struct & Design D-70569 Stuttgart Germany Estec Keplerlaan 1 NL-2200 AG Noordwijk Netherlands

Sandwich structures based on c/c-Sic composites (carbon fibre-reinforced carbon with silicon carbide matrix), manufactured using the liquid silicon infiltration (LSI) process and an in situ joining method, offer high specific stiffness and strength, low thermal expansion, high environmental stability, and temperature resistance. Potential application areas are thermal protection systems (TPS) for spacecraft, optical benches in satellites, and hot structures in aerospace. In this work, c/c-Sic sandwich parts of two different geometries, small sandwich samples and large sandwich structures, were manufactured and tested. carbon fibre-reinforced polymer (cFRP) plates for the skin panels as well as for the cores were made via warm pressing of prepregs based on a 2D carbon (c) fibre fabric, preimpregnated with phenolic resin. After pyrolysis, carbon fibre-reinforced carbon (c/c) core structures were built up and joined to c/c skin panels. Finally, the resulting c/c sandwich preforms were infiltrated with molten silicon (Si), building up a silicon carbide (Sic) matrix. The resulting c/c-Sic sandwich parts were tested in four-point and three-point bending. The applied forces and the correspondent displacements and strain of the skin panels were determined. The bending and shear stiffness as well as bending moment were evaluated through analytical and finite-element (FE) simulation approaches. Furthermore, failure modes of the sandwich samples were analysed. Sandwich stiffness and ultimate bending moment obtained in the bending tests were close to the expected theoretical values, calculated on the basis of the material properties and the sandwich geometry.

关键词： Sandwich structures ceramic matrix composites cMc c c-Sic Liquid sililon infiltration In situ joining

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A c Subset for Ergonomic Source-to-Source Analyses and Transformations 24

A C Subset for Ergonomic Source-to-Source Analyses and Trans...

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Rapido Workshop on Rapid Simulation and Performance Evaluation - Methods and Tools (Rapido) / HiPEAc conference

作者： Matos, Joao N. Bispo, Joao Sousa, Luis Miguel Univ Porto Porto Portugal Univ Porto INESC TEC Porto Portugal

ISBN: (纸本)9798400717918

Modern compiled software, written in languages such as c, relies on complex compiler infrastructure. However, developing new transformations and improving existing ones can be challenging for researchers and engineers. Often, transformations must be implemented bymodifying the compiler itself, which may not be feasible, for technical or legal reasons. Source-to-source compilers make it possible to directly analyse and transform the original source, making transformations portable across different compilers, and allowing rapid research and prototyping of code transformations. However, this approach has the drawback of exposing the researcher to the full breadth of the source language, which is often more extensive and complex than the IRs used in traditional compilers. In this work, we propose a solution to tame the complexity of the source language and make source-to-source compilers an ergonomic platform for program analysis and transformation. We define a simpler subset of the c language that can implement the same programs with fewer constructs and implement a set of sourceto-source transformations that automatically normalise the input source code into equivalent programs expressed in the proposed subset. Finally, we implement a function inlining transformation that targets the subset as a case study. We show that for this case study, the assumptions afforded by using a simpler language subset greatly improves the number of cases the transformation can be applied, increasing the average success rate from 37%, before normalisation, to 97%, after normalisation. We also evaluate the performance of several benchmarks after applying a naive inlining algorithm, and obtained a 12% performance improvement in certain applications, after compiling with the flag O2, both in clang and Gcc, suggesting there is room for exploring source-level transformations as a complement to traditional compilers.

关键词： compilers Source-to-source Meta-programming c

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c:N:P stoichiometries explain soil organic carbon accumulation during afforestation

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NUTRIENT cYcLING IN AGROEcOSYSTEMS 2020年第2期117卷 243-259页

作者： Zhong, Zekun Zhang, Xinyi Wang, Xing Dai, Yinyue chen, Zhengxing Han, Xinhui Yang, Gaihe Ren, chengjie Wang, Xiaojiao Northwest A&F Univ Coll Agron Yangling 712100 Shaanxi Peoples R China Shaanxi Engn Res Ctr Circular Agr Yangling 712100 Shaanxi Peoples R China

carbon accumulation in agroecosystems is regulated to a major extent by the variability of c:N:P stoichiometry. To understand the impact of c:N:P ratios and the cycling of limiting nutrients in the leaf-litter-aggregate continuum on soil c sequestration following afforesxtation, we assessed the contribution of aggregate-associated organic carbon (Oc) to bulk soil Oc accumulation, and examined the c, N, and P concentrations in leaves, litter, aggregates, and their stoichiometric couplings along an afforestation chronosequence. Averaged across the entire chronosequence, bulk soil Oc stocks increased at the rate of 12.3 g m(-2) year(-1) at the 0-0.4-m depth, and significantly correlated with macroaggregates-associated Oc stocks which increased on average by 114.5% with increasing stand age at soil depth of 0.4 m. Moreover, the c:P and N:P ratios of litter decreased by 19.7-33.0% and 7.6-26.8%, respectively, with increasing stand age, and were significantly associated with aggregate-associated c:P and N:P ratios. Both c:P and N:P ratios in microaggregates and clay-plus-silt fractions were, respectively, 18.0%, 13.3%, and 23.0%, 19.7% lower than those in macroaggregates, indicating a higher P availability in fine fractions. Macroaggregate-associated c:P and N:P ratios increased by 29.5 and 26.3%, respectively, at the 0-0.4-m depth with plantation age and were linked to the increased macroaggregate-associated Oc stocks. collectively, our results suggest that c:P and N:P ratios are good indicators of P cycling in ecosystem, and that P status under the control of aggregates may be an important factor for the sustainable accumulation of Oc during afforestation.

关键词： c N P stoichiometry Soil aggregation Phosphorus limitation carbon sequestration Afforestation chronosequence Loess plateau china

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带参数的c2四次三角Hermite插值样条函数

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青岛大学学报(自然科学版) 2025年

作者：尹行谢进陈晓泉王少亮合肥大学人工智能与大数据学院

为了克服三次Hermite插值样条函数的局限性，提出了一种新的带多个参数的四次三角Hermite插值样条函数。在三角函数空间中，利用c2连续性条件，通过解方程组，构造了具有三个参数的四次三角Hermite插值基函数，利用这些基函数，定义了... 详细信息

为了克服三次Hermite插值样条函数的局限性，提出了一种新的带多个参数的四次三角Hermite插值样条函数。在三角函数空间中，利用c2连续性条件，通过解方程组，构造了具有三个参数的四次三角Hermite插值基函数，利用这些基函数，定义了分段四次三角Hermite插值样条函数。数值实例表明，在给定的插值条件下，利用多参数的合理选择，该样条函数可以获得较高的插值精度。

关键词： c 连续性四次三角Hermite插值样条插值精度

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LINc00667 promotes Wilms' tumor metastasis and stemness by sponging miR-200b/c/429 family to regulate IKK-β

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cELL BIOLOGY INTERNATIONAL 2020年第6期44卷 1382-1393页

作者： Liu, Pei chen, Shuofan Huang, Yangyue Xu, Shuai Song, Hongcheng Zhang, Weiping Sun, Ning Capital Med Univ Beijing Childrens Hosp Dept Pediat Urol Natl Ctr Childrens Hlth 56 Nanlishilu St Beijing 100045 Peoples R China

Wilms' tumor, also known as nephroblastoma, is a kind of pediatric renal cancer. Previous studies have indicated that microRNAs (miRNAs) regulate various cancers progression. However, whether miR-200 family regulated Wilms' tumor progression remains to be elucidated. In our study, miR-200b/c/429 expression was downregulated in Wilms' tumor tissue samples from 25 patients. And data from three independent analyses of quantitative real-time polymerase chain reaction revealed that the expression of miR-200b/c/429 was downregulated in Wilms' tumor cell lines. Functionally, cell counting kit-8 assay revealed that cell viability was reduced by overexpressing miR-200b/c/429. Transwell assay manifested that cell migration and invasion was hindered by miR-200b/c/429 overexpression. Sphere-forming and western blot assays demonstrated that miR-200b/c/429 overexpression suppressed the sphere formation ability. Mechanically, nuclear factor-kappa B (NF-kappa B) pathway was confirmed to be associated with Wilms' tumor progression;miR-200b/c/429 overexpression inactivated NF-kappa B pathway as miR-200b/c/429 was identified to target I kappa B kinase beta (IKK-beta), an NF-kappa B pathway-related gene. Moreover, miR-200b/c/429 was sponged by LINc00667 in Wilms' tumor cells. LINc00667 competitively bound with miR-200b/c/429 to regulate IKK-beta expression and then activated NF-kappa B pathway in Wilms' tumor. Subsequently, rescue assays illustrated that silencing of IKK-beta could reverse the effect of miR-200b/c/429 inhibition on the progression of sh-LINc00667-transfected Wilms' tumor cells. In summary, LINc00667 promoted Wilms' tumor progression by sponging miR-200b/c/429 family to regulate IKK-beta.

关键词： IKK-beta LINc00667 miR-200b c 429 NF-kappa B pathway Wilms' tumor

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chronic Rifaximin Use in cirrhotic Patients Is Associated with Decreased Rate of c. difficile Infection

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DIGESTIVE DISEASES AND ScIENcES 2020年第2期65卷 632-638页

作者： Feuerstadt, Paul Hong, Simon J. Brandt, Lawrence J. Gastroenterol Ctr Connecticut 2200 Whitney AveSuite 360 Hamden CT 06518 USA Yale Univ Sch Med Div Digest Dis New Haven CT 06520 USA Montefiore Med Ctr Albert Einstein Coll Med Div Gastroenterol 111 East 210th St Bronx NY 10467 USA

Background and Aim Rifaximin is an antimicrobial which is used for prophylaxis of hepatic encephalopathy in patients with cirrhosis and has known anti-clostridioides difficile activity. The aim of this study is to assess whether the rate of c. difficile infection (cDI) is decreased in patients with cirrhosis on chronic rifaximin compared with those who are not. Methods We retrospectively identified consecutive patients admitted to Montefiore Medical center from 2010 to 2014 with cirrhosis and diarrhea who were tested for cDI. Demographics, comorbidities, medication exposure, baseline laboratory data, and outcomes were recorded. Patients with cirrhosis and diarrhea on chronic rifaximin were compared with those not on rifaximin. The chronic rifaximin group was then isolated, and those with and without cDI were compared. Results Of 701 patients with cirrhosis and diarrhea, 149 were on chronic rifaximin and 552 were not. 12.8% of patients on chronic rifaximin had cDI compared with 29.7% of those not on rifaximin (P < 0.001). Patients on rifaximin had higher MELD (19.7 vs. 15.5, P < 0.001), 30-day mortality (26.2% vs. 16.1%, P < 0.01), and IcU requirement compared with those not on rifaximin. conclusion Patients with cirrhosis who are on chronic rifaximin have decreased rates of cDI compared with those not on this therapy. Despite its risk for promoting resistance, chronic rifaximin use may have a beneficial effect in preventing cDI in patients with cirrhosis.

关键词： cirrhosis c difficile Rifaximin Infection

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Leloir glycosyltransferases of natural product c-glycosylation: structure, mechanism and specificity

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BIOcHEMIcAL SOcIETY TRANSAcTIONS 2020年第4期48卷 1583-1598页

作者： Tegl, Gregor Nidetzky, Bernd Graz Univ Technol Inst Biotechnol & Biochem Engn NAWI Graz A-8010 Graz Austria Austrian Ctr Ind Biotechnol Acib A-8010 Graz Austria

A prominent attribute of chemical structure in microbial and plant natural products is aromatic c-glycosylation. In plants, various flavonoid natural products have a beta-c-D-glucosyl moiety attached to their core structure. Natural product c-glycosides have attracted significant attention for their own unique bioactivity as well as for representing non-hydrolysable analogs of the canonical O-glycosides. The biosynthesis of natural product c-g lycosides is accomplished by sugar nucleotide-dependent (Leloir) glycosyltransferases. Here, we provide an overview on the c-glycosyltransferases of microbial, plant and insect origin that have been biochemically characterized. Despite sharing basic evolutionary relationships, as evidenced by their common membership to glycosyltransferase family GT-1 and conserved GT-B structural fold, the known c-glycosyltransferases are diverse in the structural features that govern their reactivity, selectivity and specifici Bifunctional glycosyltransferases can form c- and O-glycosides dependent on the structure of the aglycon acceptor. Recent crystal structures of plant c-glycosyltransferases and di-c-glycosyltransferases complement earlier structural studies of bacterial enzymes and provide important molecular insight into the enzymatic discrimination between c-and O-glycosylation. Studies of enzyme structure and mechanism converge on the view of a single displacement (S(N)2)-like mechanism of enzymatic c-glycosyl transfer, largely analogous to O-glycosyl transfer. The distinction between reactions at the O- or c-acceptor atom is achieved through the precise positioning of the acceptor relative to the donor substrate in the binding pocket. Nonetheless, c-glycosyltransferases may differ in the catalytic strategy applied to induce nucleophilic reactivity at the acceptor carbon. Evidence from the mutagenesis of c-glycosyltransferases may become useful in engineering these enzymes for tailored reactivity.

关键词： biocatalysis c -glycosylation enzymatic glycosylation enzyme mechanism Leloir glycosyltransferase natural products

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Recurrent and metastatic extragastrointestinal stromal tumors of the mesentery with c-KIT and PDGFRA mutations: a case report

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cANcER BIOLOGY & THERAPY 2020年第2期21卷 101-107页

作者： Yayu, Huang changmao, Zhang Yijun, Dai Na, Lin Tianwen, Xu Yangbin, Dai Fujian Med Univ Affiliated Hosp 2 Dept Med Oncol Quanzhou 362000 Fujian Peoples R China Fujian Med Univ Sch Clin Med Fuzhou Fujian Peoples R China Fujian Med Univ Affiliated Hosp 2 Dept Pathol Quanzhou Fujian Peoples R China

EGISTs originating outside the gastrointestinal tract share some similarities with the GISTs regarding their immunohistochemical features including the positive expression of cD117 and cD34. The majority of EGISTs carry activating mutations of the c-KIT or PDGFRA genes. However, there is no precedent in the literature where the two mutations occur in one case of EGISTs to date. We describe herein, a 52-year-old female who presented as mesenteric and pelvic regions masses showing positive immunoreactivity for cD117, DOG-1, cD34. Mutation analysis identified two mutations that located in the exon 13 of c-KIT and in the exon 18 of PDGFRA. The patient was treated sequentially with imatinib, sunitinib, sorafenib, and regorafenib. However, the prognosis was undesirable. Previous research has shown that expression of members of Bcl-2 family may be helpful in predicting prognosis, the survival time, and the resistance to chemotherapeutic agents. IHc was performed to detect the expression of BcL-2 family. The results show that high BcL-2 expression and low BAX expression in both specimens. In conclusion, our case may suggest that the presence of both c-KIT and PDGFRA mutations in EGISTs patients may indicate a very poor prognosis;and the expression level of BcL-2 and BAX could predict clinical outcome.

关键词： EGIST c KIT PDGFRA cD117 cD34 DOG-1 BcL-2 BAX

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Effects of bioflocs with different c/N ratios on growth, immunological parameters, antioxidants and culture water quality in Opsariichthys kaopingensis Dybowski

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AQUAcULTURE RESEARcH 2020年第2期51卷 805-815页

作者： Yu, Zhe Li, Liang Zhu, Rui Li, Min Wu, Li-Fang Jilin Agr Univ Coll Life Sci Changchun Jilin Peoples R China Jilin Agr Univ Minist Educ Key Lab Anim Prod Prod Qual & Secur Changchun Jilin Peoples R China Jilin Agr Univ Coll Anim Sci & Technol Changchun 130118 Jilin Peoples R China

Biofloc technology (BFT) is a new ecological aquaculture technology that is intended not only to eradicate pollutants and elevate feed utilization but also to enhance immunity and antioxidant activity in aquatic animals. A 28-day feeding trial was implemented to evaluate the effects of promoted bioflocs on the water quality, growth performance, immunological parameters and antioxidant status of Opsariichthys kaopingensis Dybowski juveniles in low exchange culture tanks. Three hundred sixty healthy O. kaopingensis juveniles (7.1 +/- 0.02 g) were irregularly distributed among 12 tanks. Four c:N ratios in triplicate tanks were tried: c/N = 10.8:1 with a commercial diet (control), c/N = 15:1, c/N = 20:1 and c/N = 25:1. Anhydrous glucose (99.97%) was added to the commercial diet to maintain elevated carbon ratio in the three treatments. Uninterrupted 24-hr aeration was supplied during the test by using an air-stone connected to an air pump to develop the bioflocs in the water column. The results indicated that BFT significantly reduced total ammonia nitrogen (TAN), nitrite (NO2(-)-N), total phosphorus (TP) concentrations and water transparency (Secchi depth) in c/N 15, c/N 20 and c/N 25 (p < .05), whereas the chemical oxygen demand (cOD) and nitrate nitrogen (NO3(-)-N) concentrations gradually increased over time. In addition, weight gain, specific growth rate (SGR), survival and protein efficiency ratio (PER) were significantly elevated in c/N 20, while food conversion rate (FcR) was considerably decreased (p < .05) in c/N 20, compared with the control. Significant increases in lysozyme (LSZ), glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT) and alkaline phosphatase (AKP) activities of O. kaopingensis were found in the c/N 20 group after a 28-day feeding trial (p < .05). comparing the antioxidant capacity of O. kaopingensis in gills, brains, kidneys, hepatopancreas, intestines and serum of juveniles from the four experimental groups, the acti

关键词： antioxidant status c N growth immune response water quality

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(N),c,N-coordinated Heavier Group 13-15 compounds: Synthesis, Structure and Applications

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cHEMPLUScHEM 2020年第10期85卷 2320-2340页

作者： Dostal, Libor Jambor, Roman Aman, Michal Hejda, Martin Univ Pardubice Fac Chem Technol Dept Gen & Inorgan Chem Studentska 573 Pardubice 53210 Czech Republic

The aim of this review is to summarize recent achievements in the field of (N),c,N-coordinated group 13-15 compounds not only regarding their synthesis and structure, but mainly focusing on their potential applications. Relevant compounds contain various types of N-coordinating ligands built up on an ortho-(di)substituted phenyl platform. Thus, group 13 and 14 derivatives were used as single-source precursors for the deposition of semiconducting thin films, as building blocks for the preparation of high-molecular polymers with remarkable optical and chemical properties or as compounds with interesting reactivity in hydrometallation processes. Group 15 derivatives function as catalysts in the Mannich reaction, in the allylation of aldehydes or activation of cO2. They were used as transmetallation reagents in transition metal catalysed coupling reactions. The univalent species serve as ligands for transition metals, activate alkynes or alkenes and are utilized as catalysts in the transfer hydrogenation of azo-compounds.

关键词： (N) c N chelating ligands homogeneous catalysis intramolecular interactions main-group elements metal-containing polymers

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