P(BS-co-DGA)共聚物的合成和降解性的研究

改变二乙醇酸(DCA)的添加量和聚丁二酸丁二醇酯PBS缩合聚合,得到了数均分子质量达6.5万以上的P(BS-co-DGA)二元无规共聚物.使用核磁共振表征了共聚物的化学结构,根据不同DGA的添加量对共聚物的相对分子质量、热性质、力学性能、降解性的影响等进行了研究.结果表明P(BS-co-DGA)共聚物在较短的反应时间内具有相对高的数均分子质量,分子量分布在2左右;随着DGA添加量的增加,共聚物的Tm和△Hm呈降低趋势;但是所有共聚物的热稳定性没有大的改变,热分解温度均在300℃以上;DGA添加量为2%时在堆肥中的降解速度最快.     

The Potential of Using an Autogenous Tendon Graft by Injecting Bone Marrow Aspirate in a Rabbit Meniscectomy Model

Bone marrow aspirate (BMA) is an excellent source of cells and growth factors and has been used successfully for bone, cartilage, and soft-tissue healing. This study aimed to investigate the histological and biomechanical properties of autogenous tendon graft by injecting BMA and its protective effect against degenerative changes in a rabbit model of meniscal defects. Adult white rabbits were divided into untreated, tendon, and tendon + BMA groups, and meniscal defects were created in the knees. The tendon graft and articular cartilage status were evaluated by macroscopic and histological analysis at 4, 12, and 24 weeks postoperatively among the three groups. The tendon graft in the tendon and tendon + BMA groups were used for biomechanical evaluation at 4, 12, and 24 weeks postoperatively. The meniscal covering ratio in the tendon + BMA group was better than that in the tendon and untreated groups at 12 and 24 weeks postoperatively. The matrix around the central portion of cells in the tendon + BMA group was positively stained by safranin O and toluidine blue staining with metachromasia at 24 weeks. The histological score of the tendon graft in the tendon + BMA group was significantly higher than that in the untreated and tendon groups at 12 and 24 weeks postoperatively. In the tendon + BMA group, cartilage erosion was not shown at 4 weeks, developed slowly, and was better preserved at 12 and 24 weeks compared to the untreated and tendon groups. Histological scores for the articular cartilage were significantly better in the tendon + BMA group at 24 weeks. The compressive stress on the tendon graft in the tendon + BMA group was significantly higher than that in the tendon group at 12 weeks postoperatively. Transplantation of autogenous tendon grafts by injecting BMA improved the histologic score of the regenerated meniscal tissue and was more effective than the tendon and untreated group for preventing cartilage degeneration in a rabbit model of massive meniscal defects.     

基于大规模语料库的新词检测

自然语言的发展提出了快速跟踪新词的要求.提出了一种基于大规模语料库的新词检测方法,首先在大规模的Internet生语料上进行中文词法切分,然后在分词的基础上进行频度统计得到大量的候选新词.针对二元新词、三元新词、四元新词等的常见模式,用自学习的方法产生3个垃圾词典和一个词缀词典对候选新词进行垃圾过滤,最后使用词性过滤规则和独立词概率技术进一步过滤.据此实现了一个基于Internet的进行在线新词检测的系统,并取得了令人满意的性能.系统已经可以应用到新词检测、术语库建立、热点命名实体统计和词典编纂等领域.     

Analysis of Selenoprotein F Binding to UDP-Glucose:Glycoprotein Glucosyltransferase (UGGT) by a Photoreactive Crosslinker

In the endoplasmic reticulum glycoprotein quality control system, UDP-glucose : glycoprotein glucosyltransferase (UGGT) functions as a folding sensor. Although it is known to form a heterodimer with selenoprotein F (SelenoF), the details of the complex formation remain obscure. A pulldown assay using co-transfected SelenoF and truncated mutants of human UGGT1 (HUGT1) revealed that SelenoF binds to the TRXL2 domain of HUGT1. Additionally, a newly developed photoaffinity crosslinker was selectively introduced into cysteine residues of recombinant SelenoF to determine the spatial orientation of SelenoF to HUGT1. The crosslinking experiments showed that SelenoF formed a covalent bond with amino acids in the TRXL3 region and the interdomain between βS2 and GT24 of HUGT1 via the synthetic crosslinker. SelenoF might play a role in assessing and refining the disulfide bonds of misfolded glycoproteins in the hydrophobic cavity of HUGT1 as it binds to the highly flexible region of HUGT1 to reach its long hydrophobic cavity. Clarification of the SelenoF-binding domain of UGGT and its relative position will help predict and reveal the function of SelenoF from a structural perspective.     

Data-driven modelling of turbine wake interactions and flow resistance in large wind farms

Turbine wake and local blockage effects are known to alter wind farm power production in two different ways: (1) by changing the wind speed locally in front of each turbine and (2) by changing the overall flow resistance in the farm and thus the so-called farm blockage effect. To better predict these effects with low computational costs, we develop data-driven emulators of the ‘local’ or ‘internal’ turbine thrust coefficient $C_T^{\ast }$ as a function of turbine layout. We train the model using a multi-fidelity Gaussian process (GP) regression with a combination of low (engineering wake model) and high-fidelity (large eddy simulations) simulations of farms with different layouts and wind directions. A large set of low-fidelity data speeds up the learning process and the high-fidelity data ensures a high accuracy. The trained multi-fidelity GP model is shown to give more accurate predictions of $C_T^{\ast }$ compared to a standard (single-fidelity) GP regression applied only to a limited set of high-fidelity data. We also use the multi-fidelity GP model of $C_T^{\ast }$ with the two-scale momentum theory (Nishino & Dunstan 2020, J. Fluid Mech. 894, A2) to demonstrate that the model can be used to give fast and accurate predictions of large wind farm performance under various mesoscale atmospheric conditions. This new approach could be beneficial for improving annual energy production (AEP) calculations and farm optimization in the future.     

Numerical study of the correlation between fish school arrangement and propulsive performance

Artificial Life and Robotics - We focus on the distances in flow direction and its vertical direction on three fish school arrangements, and correlate the fish school in uniform flow with fluid...