摘要：The global demand for effective skin injury treatments has prompted the exploration of tissue engineering *** three-dimensional(3D)bioprinting has shown promise,challenges persist with respect to achieving timely and compatible solutions to treat diverse skin *** situ bioprinting has emerged as a key new technology,since it reduces risks during the implantation of printed scaffolds and demonstrates superior therapeutic ***,maintaining printing fidelity during in situ bioprinting remains a critical challenge,particularly with respect to model layering and path *** study proposes a novel optimization-based conformal path planning strategy for in situ bioprinting-based repair of complex skin *** strategy employs constrained optimization to identify optimal waypoints on a point cloud-approximated curved surface,thereby ensuring a high degree of similarity between predesigned planar and surface-mapped 3D ***,this method is applicable for skin wound treatments,since it generates 3D-equidistant zigzag curves along surface tangents and enables multi-layer conformal path planning to facilitate the treatment of volumetric ***,the proposed algorithm was found to be a feasible and effective treatment in a murine back injury model as well as in other complex models,thereby showcasing its potential to guide in situ bioprinting,enhance bioprinting fidelity,and facilitate improvement of clinical outcomes.

摘要：Autologous bone marrow-derived mesenchymal stem cells(BMSCs)have been shown to promote osteogenesis;however,the effects of allogeneic BMSCs(allo-BMSCs)on bone regeneration remain ***,we explored the bone regeneration promotion effect of allo-BMSCs in 3D-printed autologous bone particle(ABP)***,we concurrently printed scaffolds with polycaprolactone,ABPs,and allo-BMSCs for appropriate support,providing bioactive factors and seed cells to promote *** vitro studies showed that ABP scaffolds promoted allo-BMSC osteogenic *** vivo studies revealed that the implantation of scaffolds loaded with ABPs and allo-BMSCs into canine skull defects for nine months promoted *** experiments suggested that only a small portion of implanted allo-BMSCs survived and differentiated into vascular endothelial cells,chondrocytes,and *** implanted allo-BMSCs released stromal cell-derived factor 1 through paracrine signaling to recruit native BMSCs into the defect,promoting bone *** study contributes to our understanding of allo-BMSCs,providing information relevant to their future application.

摘要：The recovery and reconstruction of central nervous system function after spinal cord injury(SCI)is a worldwide *** difficulty lies in the feasibility issue of new axons passing through the injured area and the negative effect of scarring after *** a biological material,the human amniotic membrane(HAM)has the advantages of protecting nerve growth,inhibiting scar formation,and promoting neovascularization,but its weak physical properties are difficult to apply in treating *** this study,HAMs were first decellularized and then chemically grafted with methacrylic ***,the composite was photocrosslinked with gelatin methacrylate to prepare a cross-network biological *** final complexes prepared by appeal were used for in vitro and in vivo studies of SCI in rats,*** the in vitro experiment,the composite scaffold inherited abundant biological factors from the amniotic membrane and had the physical properties of a hydrogel,thus providing a favorable environment for the growth and development of neurons and blood *** the in vivo experiment,the composite reduced scarring and promoted the growth of new ***,the composite scaffolds can stably simulate the extracellular microenvironment in SCI defects,regulate pathological changes,and promote the generation of new ***,decellularized HAM hydrogels are promising biocomposite materials for central nerve repair after SCI.

摘要：Due to their special anatomical and physiological features,central nervous system diseases still presented challenges,despite the fact that some advances have been made in early diagnosis and precision *** of the complexities in treating tumors is the tumor microenvironment,which includes mesenchymal stem cells(MSCs)that exhibit tumor tropism and can be used for cell ***,whether MSCs promote or suppress gliomas is still unclear,especially in glioma *** this study,a coaxial microfiber was designed to mimic the tumor microenvironment and to reveal the effect of MSCs on glioma *** fiber shell was composed of MSCs and alginate,and the core was filled with U87 MG(glioblastoma)cells and gelatin *** Shell-MSC/Core-U87 MG microenvironment improved the proliferation,survival,invasion,metastasis,and drug resistance of glioma cells,while simultaneously maintaining the stemness of glioma *** summary,coaxial extrusion bioprinted Shell-MSC/Core-U87 MG microfiber is an ideal platform for tumor and stromal cell coculture to observe tumor biological behavior in vitro.

摘要：Overview and research infrastructure As one of the leading laboratories in the interdisciplinary field of additive manufacturing and bio-3D printing,the Bio-Manufacturing Center at Tsinghua University is highly dedicated to conducting cutting-edge research in the emerging field of *** latter is comprised of research involving biomaterials,living cells,proteins,and/or other biological compounds as basic building blocks to fabricate biomimetic structures,in vitro functional biological models and/or cellular systems with application to tissue engineering,regenerative medicine,disease pathogenesis,drug screening,and tissue/organ-on-a-chip.

摘要：随着信息技术的发展,如何将信息技术与学科教学进行整合显得愈加重要。整合技术的学科教学法知识框架(TPACK),强调信息技术、教学知识和学科知识之间的多重联系。本文针对信息素养课程改革现状,基于TPACK框架从教学内容、教学方法和教学技术3个方面进行教学设计和应用。通过实证研究发现,基于TPACK框架的信息素养课程教学设计效果显著,提升了学生文献获取、阅读分析及团队协作等多方面的能力。

摘要：针对无差拍预测电流控制中,电流指令突变可能导致的电压不足的问题,提出一种动态优化电流参考的过调制方法。首先,基于电压矢量六边形和当前电流采样值,对两拍后的电流矢量六边形进行预测。所得映射即为两拍后的电流可行域,从而利于实现精确的电流轨迹规划;其次,当进入过调制区时,选取预测的电流矢量六边形与期望电流轨迹的交点作为优化的电流参考值。这一步旨在抑制电压不足引起的电流轨迹漂移同时确保最大的电压利用率,并设计一种交点的通用简化运算方法。将无差拍预测电流控制与所提出过调制方法相结合,能够在过调制区实现动态的电流参考值优化以及无差拍响应,实现对任意电流轨迹的精准追踪。以id=0和id=-0.5iq轨迹追踪为例,将所提出策略与传统方法进行比较。过调制区的动态优化电流参考在仿真和实验中均得到了验证,并展示了所提策略优异的电流轨迹追踪性能。

摘要：为满足燃气轮机对高温、高压滑动轴承的需求,基于常规滑动轴承设计理论以及对高温环境下润滑理论的研究及应用技术,设计了一种适用于船用燃气轮机高温、高压、高速等复杂工况的可倾瓦滑动止推轴承,建立了热流体动压润滑计算模型对轴承进行了数值模拟分析,搭建了全尺寸性能测试试验台,开展了滑动止推轴承稳态特性的试验研究。研究结果表明:滑动轴承瓦块最高油膜压力达到6.6 MPa,而出油边的最高温度达到120℃,其运行的参数均远高于常规滑动轴承,油膜压力的试验值和仿真值基本接近,验证了设计的合理性;通过600 h的实机考核证明了本文所设计的滑动轴承在极限工作条件下的可靠性。

摘要：为研究拓扑路网中稀疏数据路段行程速度与其空间关联道路间的耦合影响,以路网中空间距离分布为基础,明确了道路空间关联指数(road spatial correlation index,RSCI)定义和计算方法,构建了一种面向道路行程速度稀疏数据修复和可解释性模型。首先,在传统轮盘算法基础上提出了针对选择操作和算子的改进遗传算法(improved genetic algorithm,IGA),利用自适应机制优化个体选择概率,通过设置常数λ解决后续优秀个体选择概率偏低缺陷,提高模型收敛性能。其次,利用IGA和K折交叉验证(K-fold cross validation,K-Fold CV)实现极限梯度提升算法(extreme gradient boosting,XGBoost)中n_estimators、Learning_rate、Min_child_weight、Max_depth超参数寻优。然后,利用SHAP(shapey additive explanation,SHAP)方法对XGBoost模型各特征重要性开展全局解释和个体样本溯源分析。最后,以目标道路行程速度为输出、连接道路行程速度为特征输入进行实例验证。研究结果表明:IGA-XGBoost组合算法f_(MAE)、f_(RMSE)分别为1.95、2.66,R^(2)为0.941,较GA-XGBoost提高0.4%,模型运行时间为1.532 s,较GA-XGBoost运行时间减少7.6%,组合算法预测精度更高,迭代效率有明显提升;以SHAP值标定特征重要性下,连接道路特征重要性与其RSCI呈正相关,RSCI数值越大,连接道路对预测结果贡献越高;在连接道路数量不足时,以SHAP值排名前3的连接道路对目标道路数据填补时,模型f_(MAE)、f_(RMSE)、R^(2)分别为2.53、3.30、0.905,仍能取得较好的数据修复精度,证明了方法的适用性。研究结果可为城市道路行程车速数据修复填补提供新思路。

摘要：城市化驱动下,乡村地区土地利用/覆被(LULC)发生明显变化,进而导致了地表热环境的改变。然而,乡村地表温度(LST)在不同尺度上与景观格局的关系还缺乏理解。本研究以富春江流域乡村地区为例,利用相关性分析、空间自相关分析和地理加权相关系数分析等方法,探讨了不同分析尺度下(300、600、900、1200、1500、1800、2100 m和乡镇尺度),1990年和2020年夏季不同地类景观格局对LST的影响。结果表明:(1)1990—2020年耕地、林地是主要用地类型,30年间耕地面积大量减少,主要转化为工业用地、城镇建设用地和农村居民点用地。(2)中度升温区及重度升温区主要分布于富春江两岸的城镇建设用地、农村居民点用地和工业用地聚集区。此外,随分析单元尺度增加,单元间LST的差异逐渐模糊。(3)不同地类景观格局指数与LST的相关性强弱程度依次为城镇建设用地>工业用地>耕地>水体>农村居民点用地>林地,且随尺度增大表现出不同的变化趋势。其中,斑块面积百分比(PLAND)指数对LST的影响最强。耕地减少,城镇建设用地和工业用地增加是局部LST上升的主要原因,农村居民点用地增加对LST的影响相对较弱。林地变化不明显,但对地表热环境具有缓解作用。(4)城镇建设用地、工业用地景观格局指数与LST之间存在明显空间自相关和空间溢出效应。研究结果有助于理解乡村地区土地利用/覆被变化对地表温度的影响,并为未来降低城市化对乡村环境负面影响的解决方案提供了理论依据。